Out of autoclave apparatus

Abstract

The invention concerns an out-of-autoclave thermoplastic consolidation apparatus and method comprising a one or more electrically conductive conduits having internal passages arranged in use to communicate a coolant from an inlet to an outlet of the one or more electrically conductive conduits.

Description

[0001] OUT OF AUTOCLAVE APPARATUS

[0002] Background

[0003] The present invention is concerned with an alternative apparatus and method for the consolidation of thermoplastic composite parts.

[0004] Conventionally, consolidation of thermoplastic parts is achieved using an autoclave and vacuum bagging system as will be understood by the person skilled in the art. In a conventional autoclave process the autoclave process exhibits cycle times of 4-7 hours, depending on size of component & complexity and matrix material.

[0005] Developments in manufacturing thermoplastic parts resulted in an alternative method consisting of the steps of heating, consolidation and cooling where the heating process is achieved using induction. Such techniques involve selecting specific temperatures and pressures (which are a function of the selected matrix material) and establishing the time needed for heating, consolidation & cooling of the chosen materials in the specific tooling being used.

[0006] Such induction tooling involved a rigid heated tool (above 400°C) with integrated round tubing induction coils to generate an alternating magnetic field. Separate cooling channels (typically conveying water) are used to cool the tool. The process involves placing the composite material between the heated blocks and applying a force to the blocks to generate a consolidation pressure in the composite material. Pressure is generally applied with a hydraulic press.

[0007] Whilst these conventional techniques have allowed composite components to be manufactured, the inventors have established that when the heating and cooling is performed with a rigid tool (where the coil and cooling is integrated in the rigid body of the tool), the mass to heat and cool is relatively high. This leads to longer cycle times and requires higher power to heat and cool the rigid tool. Limitations were also identified with respect to manufacturability of cooling channels for complex and large parts. Furthermore, applying pressure with a hydraulic press limits the usable total tool area due to the significantly higher capital investment costs for a hydraulic press. The inventor has established an alternative approach to (co-)consolidation of components which avoids the high cycle time and labour intensive autoclave technique, and additionally improves on a conventional induction consolidation tool arrangement. Furthermore, the apparatus and method described herein advantageously reduces energy consumption and waste materials generation. Still further according to a process and apparatus described herein the process cycle time can be significantly reduced thereby making it a process suitable for high rate production.

[0008] Summary of the Invention

[0009] Aspects of the invention are set out in the accompanying claims.

[0010] Viewed from a first aspect there in provided, an out-of-autoclave thermoplastic consolidation apparatus comprising an upper forming tool and an opposing lower forming tool, the upper forming tool and lower forming tool defining a space there between for forming a part, the apparatus further comprising: one or more electrically conductive conduits, the conduits comprising an internal passage arranged in use to communicate a coolant from an inlet to an outlet of the one or more electrically conductive conduits, wherein the electrically conductive conduits are arranged proximate to one or both of the upper and lower forming tools, and wherein the one or more electrically conductive conduits are arranged in use to be excited by an electrical alternating current.

[0011] According to such an apparatus a counterintuitive cooling system is integrated into an electrical induction system for a consolidation tool. Specifically, the heat that is used to effect the consolidation is created through induction which causes the forming tools to increase in temperature. Electrically exciting the electrically conductive coils with an electrical alternating current creates a magnetic field which generates heat within a forming tool associated (that is proximate to) the respective coil(s). The amount of heat created within a respective tool may advantageously be selectively controlled using the electrical supply or supplies.

[0012] The temperature of the conductive coils, and in turn, the consolidation tool, is controlled using an internal coolant passage within and extending along the coils. By introducing a coolant into the coil passage the temperature of the coil itself can be controlled.

[0013] This provides a number of technical and operational advantages. For example the induction heating concept:

[0014] Allows for more efficient heating, as tool itself is heated;

[0015] Allows for highly controlled cooling;

[0016] Provides less limitations when compared to a conventional induction consolidation tool arrangement;

[0017] Allows for tool to be heated and cooled faster which decreases cycle times;

[0018] Allows for tool thermal mass to be limited, due to external coil and cooling layout; Allows for increased temperature uniformity and quality of final piece, as tool material may be selected based on its Curie temperature. Curie temperature acts as a fail-safe and prevents the composite from being heated excessively. In effect, selecting the Curie temperature at a predetermined level means that at that temperature the effects of the magnetic field dissipate and so too does the heating effect.

[0019] The electrically conductive conduits may advantageously be separated from a respective forming tool by an electrical and / or thermal insulator layer. Such a layer prevents any electrical connection between the coil and the metallic forming tool. Additionally, by selecting an appropriate material, heat transfer can be balanced for heating and cooling.

[0020] The one or more electrically conductive conduits may be in the form of hollow metallic tubes through which a coolant may flow and which are electrical conductors. Thus an integrated induction coil and cooling system can be realised. Excitation of the metallic tubes with a suitable current creates the magnetic field that heats the forming tools. Simultaneously controlling a coolant within the hollow tubes controls the temperature of the coils themselves and surrounding components of the tool.

[0021] To generate the magnetic fields in the coils, the one or more electrically conductive conduits may be electrically connected to an alternating current supply.

[0022] The electrical supply may be common to the conductive conduits. In another arrangement the one or more electrically conductive conduits may be electrically connected to electrical supplies operating at different and / or selectively controllable frequencies. Thus, the magnetic fields and thereby the heat generated can be controlled. By providing a plurality of independent conductive conduits, each connected to a separate and independently controllable supply, the heat distribution across the forming tool can be carefully controlled. Different heat zones may be created at, for example, regions where the consolidating part is thicker. This provides great control for the consolidation process and allows complex parts to be formed.

[0023] The conductive conduits may have any suitable profile. However, advantageously, the one or more electrically conductive conduits may have a square or rectangular cross-section defining an internal passage for communicating coolant there through. Rectangular or square crosssectioned conduits provide a number of advantages. For example, electrically exciting such a conduit provides more uniform heating when compared to heating by round coils due to fewer cold gaps. Furthermore, such cross-sections can advantageously accommodate the compressive loads of the tool (discussed further below). Specifically, the vertical sides of the conduits are strong in compression allowing for higher compressive consolidation forces.

[0024] The outer geometry of the conduits may also be selected so as to be complementary to the forming tool shapes. This allows for effective heat transfer to forming tools that are non- or partially non-planar, for example curved profiles. Heat and loads can therefore be effectively transmitted.

[0025] The coolant may be communicated into the conduit(s) via at least one inlet and at least one outlet to allow a coolant to pass there through. A manifold arrangement may also be used.

[0026] The coils may be arranged in any suitable formation so as to apply heat across the forming tool surface. The coils may for example be in a reciprocating or serpentine profile such that (a) the heat generated is distributed across the surface of the forming tool and (b) the coolant is caused to flow backwards and forwards across the flowing tool profile / area to effect cooling.

[0027] A single continuous coolant path may be provided or alternatively a plurality of coolant paths cooling different conduits. This may advantageously allow for specific temperature control. The tooling arrangement may also incorporate temperature sensors in cooperation with flow control valve such that forming tool temperatures can be specifically controlled in real time during the consolidation process.

[0028] During a consolidation process a compression load is advantageously applied to the stack as the stack is heated in the tool. Specific temperature and pressure profiles may be applied during the consolidation process. This also includes a cooling profile where induction heating may be deactivated and cooling continued or intensified to quickly cool the tool.

[0029] To effect the compressive loading during the consolidation process the tool may incorporate one or more expandable elements arranged in use to apply a biasing force causing the upper and lower forming tools to be pressed or biased together.

[0030] Advantageously because of the manner in which the induction coils are heated it is possible to utilise materials for the expandable elements which do not need to withstand high temperatures. This, in turn, allows materials to be used that are more flexible and compliant which they are pressurised. For example, the expandable elements may be in the form of a plurality of flexible conduits into which a fluid may be supplied.

[0031] In one arrangement the expandable elements may be in the form of one or more expandable tubes or bellows arranged in use to apply a biasing force to the upper and or lower tooling upon pressurisation with a gas or liquid.

[0032] A rigid biasing surface may optionally be located between an expandable element and an associated electrically conductive conduit. Such a rigid surface allows a more uniform force to be applied across the forming tool from the plurality of discrete expandable elements.

[0033] The tooling arrangements as a whole may also comprise a rigid housing defining a space in which the apparatus may be positioned and having internal surfaces against which the expandable elements may be biased. Thus, expansion of the expandable elements against the inner surface of the rigid housing allows the consolidation pressure needed for consolidation to be achieved.

[0034] As well as expandable elements extending generally horizontally across one or both forming tool surfaces, the tool may additionally be provided with expandable elements arranged perpendicularly to the horizontal expandable elements. In effect horizontal biasing forces may then be applied as well as vertical forces. Components with beams and ribs may therefore be formed.

[0035] The upper and lower forming tools are advantageously formed of materials that can be excited by the magnetic field generated by the induction coils. This may be any ferrous material such as steel or stainless steel or alloys thereof.

[0036] The upper and lower forming tools may also be formed from a material have a predetermined Curie temperature. The Curie temperature of the forming tools is the temperature above which the forming tools lose their magnetic properties. The effect of an induction coil on the forming tools can therefore be reduced at the Curie temperature. Selecting a material for the consolidation tool that has a Curie temperature approximate to the thermoplastic processing temperature advantageously enables automatic decoupling of the forming tool and the magnetic field at the Curie temperature, which prevents overheating during the consolidation process, and provides equalization of the temperature distribution of the forming tool. Viewed another aspect there is provided an out-of-autoclave method of consolidating a thermoplastic part using a consolidating apparatus, the consolidating apparatus comprising an upper forming tool and an opposing lower forming tool, the upper forming tool and lower forming tool defining a space there between for forming a part, the apparatus further comprising: one or more electrically conductive conduits, the conduits comprising an internal passage arranged in use to communicate a coolant from an inlet to an outlet of the one or more electrically conductive conduits, wherein the electrically conductive conduits are arranged proximate to one or both of the upper and lower forming tools, and wherein the one or more electrically conductive conduits are arranged in use to be excited by an electrical current, the method comprising the steps of:

[0037] (A) laying a plurality of thermoplastic containing plies onto the lower forming tool to form a stack;

[0038] (B) positioning the upper forming tool onto the stack;

[0039] (C) positioning the one or more electrically conductive conduits proximate to one or both forming tools;

[0040] (D) positioning expandable elements proximate to the one or more of the electrically conductive conduits;

[0041] (E) closing a frame surrounding the apparatus against which the expandable elements may be bias;

[0042] (F) selectively applying an electrical current to the electrically conductive elements and simultaneously selectively causing a coolant to flow through the internal passages of the conduits.

[0043] The expandable elements may be activated to expand so as to bias the upper and lower forming tools together.

[0044] The one or more electrically conductive conduits may be electrically excited at different and / or selectively controllable frequencies. Drawings

[0045] Aspects of the invention will now be described, by way of example only, with reference to the accompanying figures in which:

[0046] Figure 1 graphically illustrates a conventional consolidation process;

[0047] Figure 2 shows a cross-section through a tooling apparatus according to one embodiment of an invention described herein;

[0048] Figure 3 shows a cross-section through another embodiment in which a more complex components can be formed;

[0049] Figure 4 shows one arrangement of induction coil, isolation plate and die;

[0050] Figure 5A shows a cylindrical induction element and associated flux profile versus and Figure 5B shows a square cross-section with associated flux profile;

[0051] Figure 6 illustrates a part that may be consolidated using an apparatus and method described herein.

[0052] 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 the drawings and detailed description attached hereto are not intended to limit the invention to the particular form disclosed but rather the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the claimed invention.

[0053] Any reference to prior art documents in this specification is not to be considered an admission that such prior art is widely known or forms part of the common general knowledge in the field. As used in this specification, the words “comprises”, “comprising”, and similar words, are not to be interpreted in an exclusive or exhaustive sense. In other words, they are intended to mean “including, but not limited to”. The invention is further described with reference to the following examples. It will be appreciated that the invention as claimed is not intended to be limited in any way by these examples. It will also be recognised that the invention covers not only individual embodiments but also combination of the embodiments described herein.

[0054] The various embodiments described herein are presented only to assist in understanding and teaching the claimed features. These embodiments are provided as a representative sample of embodiments only and are not exhaustive and / or exclusive. It is to be understood that advantages, embodiments, examples, functions, features, structures, and / or other aspects described herein are not to be considered limitations on the scope of the invention as defined by the claims or limitations on equivalents to the claims, and that other embodiments may be utilised and modifications may be made without departing from the spirit and scope of the claimed invention. Various embodiments of the invention may suitably comprise, consist of, or consist essentially of, appropriate combinations of the disclosed elements, components, features, parts, steps, means, etc, other than those specifically described herein. In addition, this disclosure may include other inventions not presently claimed, but which may be claimed in future.

[0055] It will be recognised that the features of the aspects of the invention(s) described herein can conveniently and interchangeably be used in any suitable combination

[0056] Detailed Description

[0057] An apparatus and method described herein are concerned with the consolidation of thermoplastic materials in a process which does not require an autoclave. This is known in the art as an ‘out-of-autoclave’ or OOA process. Specifically, the apparatus and method described herein involves a modified heated tool and expandable bladder arrangement which function together to overcome the problems with existing systems.

[0058] Figure 1 graphically illustrates a conventional consolidation process. As shown a typical thermoplastic composite autoclave consolidation process can take anywhere between 4 and 7 hours. This involves three essential stages: heating, consolidating and cooling. As shown during these three stages the temperature with the autoclave is controlled in parallel with a controlled application of pressure to the part being consolidated. High quality components can be consolidated.

[0059] However, as set out above, the inventors have established a further improvement on an induction heating process that avoids the use of an autoclave but also advantageously improves the conventional induction consolidation techniques.

[0060] According to the apparatus and method described herein the overall preparation and consolidation time T can be dramatically reduced.

[0061] Figure 2 shows a cross-section through a tooling apparatus according to one embodiment of an invention described herein.

[0062] The tooling apparatus consists of:

[0063] One or more induction coils which is / are able to generate a magnetic field;

[0064] - A mould positioned in the magnetic field which is heated by the field by virtue of being a material that is magnetic permeable;

[0065] - An electric isolator between the induction coil and the mould to prevent electrical short cuts and facilitates cooling of the mould;

[0066] - A cooling arrangement that continuously cools the coil with fluid (such as cooling water) running through the coil (a closed system) and acts as medium to cool the mould. Optionally heating multiple sides of the tool i.e. bottom / sides / top. These features will be described with reference to figure 2. Figure 2 illustrates upper and lower heating and pressure application only. It will be recognised that side heating and pressure may also additionally or alternatively be used.

[0067] The tooling arrangement comprises a rigid frame 1 against which a load can be applied so as to apply a consolidation pressure to the part within the room body or cavity. An electrical isolation plate 2 is located between the frame 1 and a plurality of copper (or other conductor) induction coils 3 which extend across the tool surface. An electrical and thermal insulator 4 is located on top of the induction coils and between the coils and the lower tool or die to separate the coils 3 and the die 5. By separating the coils 3 and the die 5 using the insulator 4, sparking is prevented without the need to fully surround the coils 3 with insulating material. Electrical shielding around the coils 3 therefore is not required. The insulator 4 may be a sheet of silicate material (or other material with the same or similar properties). Furthermore, the insulator 4, in combination with the coils 3 may provide enhanced load bearing support, and the insulator 4 may be capable of withstanding the pressure that is applied during the consolidation process. The die 5 is formed of a magnetically permeable material which can be heated using a magnetic field i.e. through induction. Steel is one such example.

[0068] By using induction coils 3 that are outside of and separate from the die 5, rather than integrated induction coils and separate cooling channels (as is the case in conventional tooling techniques), the tooling arrangement of Figure 2 enables desired consolidation temperatures to be achieved with a lower energy input and within a shorter time frame. The thickness of the (invar) billet used for the die is also reduced by 2-2.5 times compared to conventional tooling techniques, as the heating and cooling structures are not inside the die. Manufacturing of the die is also simplified, as the difficulty associated with introducing cavities for cooling channels is eliminated.

[0069] A separator foil or release agent 6 could be used on top of the lower tool to allow the consolidated part to be easily removed once consolidation has occurred. An unconsolidated and / or preconsolidated stack or ply of thermoplastic material 7 is then located on top of the lower tool. The number of layers and orientation of the layers is predetermined according to the desired properties of the component being manufactured (as will be understood by a person skilled in the art).

[0070] This may be consolidated of any suitable thermoplastic material such as, for example PEKK. The arrangement is then replicated on top of the stack 7 with an upper separator foil or release agent and upper tool or die. The upper and lower dies are provided with surface geometries defining the geometry of the desired part.

[0071] An upper (thermal and electrical) insulator and induction coil arrangement is then located on the top of the stack and an upper isolating plate.

[0072] Next a pressure arrangement 8 is located between the upper isolation plate and the upper rigid frame of the tooling. The pressure arrangements is arranged along and across the tool surface such that, in use, it applies a consolidation pressure to the stack contained within the tool frame. The pressure arrangement is not limited to the upper side.

[0073] Advantageously, in one arrangement the pressure arrangement 8 is in the form or a series of hydraulically or pneumatically inflatable tubes or bellows. Thus, increasing the pressure of a fluid, such as air, within the bellow or tubes conveniently allows a pressure to be applied to the consolidating part during the process illustrated in figure 1.

[0074] The upper thermal and electrical isolation plate prevent heat being communication (conducted) to the bellows and electrical isolation plate allowing them to be formed of materials that would otherwise soften or melt.

[0075] Furthermore, the induction coils themselves advantageously incorporate cooling channels or conduits 9. This further reduces the conduction of heat from the coils to the bellows and electrical isolation plate. Tool heating can still be realised by virtue of the induction effect and magnetic interaction with the steel tooling. Thus, only the tooling (i.e. , the die 5, the separator foil 6 and the thermoplastic material 7) becomes heated.

[0076] Such as arrangement has a much lower thermal inertia and can be heated and cooled much more quickly than conventional tooling. It also avoids expensive and complex hydraulic pressed which are conventionally used. This is achieved by control of the heat within the tool using novel induction coil cooling as described herein.

[0077] Figure 3 shows a cross-section through another embodiment in which a more complex components can be formed. The arrangement show comprises a series of side pressure bladders 10 on either side of the tool. The component being consolidated comprises a flat central portion and two opposing perpendicular beams 11 located within the steel tool 12. As described with reference to figure 1 this alternative arrangement comprises the thermal / electrical isolators 13 associated with the induction coils 14.

[0078] In an advantageous alternative arrangement, a rigid tool may be used in place of the bladders 10 depicted in Figure 3. The use of a rigid tool provides fixed contouring, ensuring that the contours of the final formed part are more accurate. The use of bladders to apply pressure to the thermoplastic material can result in thickness variations towards the edges of the formed part, as it is more difficult to control the variables and therefore the quality of the part. Therefore, the use of a rigid tool rather than membranes to apply pressure may provide a more accurately formed final part.

[0079] Figure 4 shows one arrangement of induction coil, isolation plate and die.

[0080] As shown in figure 4 a serpentine or reciprocating path is defined by a series of rectangular induction elements. The induction elements comprise an inlet and an outlet as shown and a series of loops or returns which reciprocate the flow of cooling fluid within the induction elements. Each induction element has an internal passage for communicating cooling fluid within and along the element’s length. Thus, each element can act as an inductor when an electrical current is applied and simultaneously be cooled by the internal flow of coolant, such as water for example.

[0081] The serpentine or meandering path of the induction element or coil provides current travelling in opposite directions. The upper and lower arrangements of induction coils, isolation plates and dies may be connected to separate alternating current supplies, or generators, so that there is no direct connection between the upper and lower tools. This arrangement of the induction elements or coils is less complex and requires a lower total coil length than arrangements where the coils loop from a lower tool to an upper tool (e.g., a caged system), and therefore is suitable for a larger number of applications. In a caged system, a cable must run between the upper and the lower tools, to connect each coil. Accordingly, by removing the need to connect coils of the upper and lower tools, space between the male and female tools is provided. This space provides an operator of the tooling arrangement with more room to insert, remove, or de-mould parts, and service the die. This coil arrangement also allows for a clean environment, as the need to disconnect wires with cooling water is not required. Having many cables at the back of the tool as per a caged system increases the likelihood of the tool heating up and therefore loses efficiency (even with electromagnetic shielding). By providing the upper and lower arrangements of induction coils with separate alternating current supplies, or generators, the number of cables running between the upper and lower elements of the tooling arrangement is reduced, and so the efficiency of the tooling arrangement is improved. Furthermore, this arrangement allows the alternating current supply or generator connected to one induction coil arrangement (i.e., upper or lower) to be replaced or disconnected without the need to disconnect further connections. The alternating current supply or generator may then instead be used to connect to a different tooling arrangement, allowing the consolidation process to be run on the other tooling arrangement, resulting in less downtime and greater efficiency.

[0082] To prevent the conduction of heat from the induction coils an isolator plate is positioned on top of the induction elements as shown. In one example embodiment a calcium silicate plate or layer may be used. This may be positioned between the tool and the induction coils and also between adjacent coils to further reduce heat generation outside of the tooling dies. The electrical isolator between tool and coil prevents electrical arcing.

[0083] Returning to the induction coils, as suitable cross-section may be used and any suitable internal coolant conduit may be used. However, the inventors have established that a square or rectangular cross-section of induction element advantageously couples from magnetic flux to the part per turn than a cylindrical element. This is illustrated with reference to Figure 5A which shows a cylindrical induction element and associated flux profile versus (Figure 5B) a square cross-section with associated flux profile. As illustrated a more even magnetic flux can be applied which in turn results in more uniform tool or die heating. This is a particular advantage for the consolidation process and the integrity of the consolidated part.

[0084] The square or rectangular elements also advantageously allow the compression loads used in the consolidation process to be transmitted to the die and to the part. A square or rectangular cross-section has a higher resistance to collapse through lateral compression forces.

[0085] The arrangement described herein, i.e. an induction heated pneumatic consolidation tool can advantageously heat up, cool down and add pressure more effectively due to:

[0086] The capability to apply a square or rectangular tubing induction coil which couples more flux to the tool then round tubing; The induction coil is not or partly integrated in the tool, minimizing the thermal mass to be heated up and cooled down, shortening cycle time and minimize required power;

[0087] Cooling of the tool is provided by the cooling water that runs through the rectangular coil. The coil is placed against the tool with a thin electrical and thermal insulator. No steam will occur, thus no complex and expensive cooling system is required; and

[0088] - Applying pressure by means of air pressurized bladders, minimizing investment cost to supply pressure to the thermoplastic composite.

[0089] The rectangular elements as shown in figure 4 provide a continuous path for coolant from the inlet to the outlet. The rectangular elements can also be conveniently aligned with the smooth insulator surface.

[0090] The tool is loaded prior to consolidation as follows:

[0091] (A) laying a plurality of thermoplastic containing plies onto the lower forming tool to form a stack;

[0092] (B) positioning the upper consolidation tool onto the stack;

[0093] (C) positioning the one or more electrically conductive conduits proximate to one or both consolidation tools;

[0094] (D) positioning expandable elements proximate to the one or more of the electrically conductive conduits;

[0095] (E) closing a frame surrounding the apparatus against which the expandable elements may be bias;

[0096] (F) selectively applying an electrical current to the electrically conductive elements and simultaneously selectively causing a coolant to flow through the internal passages of the conduits.

[0097] Figure 6 illustrates a part that may be consolidated using an apparatus and method described herein. As shown the component comprises a substantially planar section 20 and a perpendicular feature or rib 21. It will be recognised that complex components can be manufactured using the apparatus and methods described herein. Furthermore, the specific induction heated tooling allows for short consolidation times for thermoplastic composite parts.

Claims

CLAIMS1. An out-of-autoclave thermoplastic consolidation apparatus comprising an upper forming tool and an opposing lower forming tool, the upper forming tool and lower forming tool defining a space there between for forming a part, the apparatus further comprising: one or more electrically conductive conduits, the conduits comprising an internal passage arranged in use to communicate a coolant from an inlet to an outlet of the one or more electrically conductive conduits, wherein the electrically conductive conduits are arranged proximate to one or both of the upper and lower forming tools, and wherein the one or more electrically conductive conduits are arranged in use to be excited by an alternating electrical current.

2. An apparatus as claimed in claim 1 , wherein the electrically conductive conduits are separated from a respective forming tool by an electrical and / or thermal insulator layer.

3. An apparatus as claimed in claim 1 or claim 2, wherein the one or more electrically conductive conduits are in the form of hollow metallic tubes through which a coolant may flow and which are electrical conductors.

4. An apparatus as claimed in any preceding claim, wherein the one or more electrically conductive conduits are electrically connected to an alternating current supply.

5. An apparatus as claimed in claim 4, wherein the one or more electrically conductive conduits are electrically connected to electrical supplies operating at different and / or selectively controllable frequencies.

6. An apparatus as claimed in any preceding claim wherein the one or more electrically conductive conduits have a square or rectangular cross-section defining an internal passage for communicating coolant there through.

7. An apparatus as claimed in claim 6, wherein the one or more conductive conduits have an external geometries that are complimentary to the geometry of the part to be consolidated.

8. An apparatus as claimed in any preceding claim wherein the one or more electrically conductive conduits have at least one inlet and at least one outlet to allow a coolant to pass there through.

9. An apparatus as claimed in claim 8, wherein the one or more electrically conductive conduits are arranged in an alternating or serpentine geometry to define at least one single continuous alternating coolant passage extending across the surface of a respective forming tool.

10. An apparatus as claimed in any preceding claim further comprising one or more expandable elements arranged in use to apply a biasing force causing the upper and lower forming tools to be pressed together.

11. An apparatus as claimed in claim 10, wherein the expandable elements are in the form of a plurality of flexible conduits into which a fluid may be supplied.

12. An apparatus as claimed in claim 11 , wherein the expandable elements are in the form of one or more expandable tubes or bellows arranged in use to apply a biasing force to the upper and or lower tooling upon pressurisation with a gas or liquid.

13. An apparatus as claimed in any of claims 10 to 12, further comprising a rigid biasing surface located between an expandable element and an associated electrically conductive conduit.

14. An apparatus as claimed in any preceding claim, further comprising a rigid housing defining a space in which the apparatus may be positioned and having internal surfaces against which the expandable elements may be biased.

15. An apparatus as claimed in any preceding claim wherein the electrically conductive conduits are in the form of hollow rectangular or square copper tubes.

16. An apparatus as claimed in any of claims 10 to 13, further comprising one or more expandable elements arranged perpendicularly to the expandable elements arranged in use to apply a biasing force causing the upper and lower forming tools to be pressed together.

17. An apparatus as claimed in any preceding claim wherein the upper and lower forming tools are formed from a material having a Curie temperature approximate to a predetermined processing temperature of a thermoplastic material to be consolidated.

18. An out-of-autoclave method of consolidating a thermoplastic part using a consolidating apparatus, the consolidating apparatus comprising an upper forming tool and an opposing lower forming tool, the upper forming tool and lower forming tool defining a space there between for forming a part, the apparatus further comprising: one or more electrically conductive conduits, the conduits comprising an internal passage arranged in use to communicate a coolant from an inlet to an outlet of the one or more electrically conductive conduits, wherein the electrically conductive conduits are arranged proximate to one or both of the upper and lower forming tools, and wherein the one or more electrically conductive conduits are arranged in use to be excited by an electrical current, the method comprising the steps of :(A) laying a plurality of thermoplastic containing plies onto the lower forming tool to form a stack;(B) positioning the upper forming tool onto the stack;(C) positioning the one or more electrically conductive conduits proximate to one or both forming tools;(D) positioning expandable elements proximate to the one or more of the electrically conductive conduits;(E) closing a frame surrounding the apparatus against which the expandable elements may be bias;(F) selectively applying an electrical current to the electrically conductive elements and simultaneously selectively causing a coolant to flow through the internal passages of the conduits.

19. A method as claimed in claim 18, further comprising the step of causing the expandable elements to expand so as to bias the upper and lower forming tools together.

20. A method as claimed in claim 18 or 19, wherein the one or more electrically conductive conduits are electrically excited at different and / or selectively controllable frequencies.

Images