The invention relates to a manufacturing method for manufacturing a part made of composite material with a continuous fibre reinforcement. Further, the invention re lates to a manufacturing system for manufacturing a part made of composite mate rial with a continuous fibre reinforcement.

3D reinforced composite structures are more and more relevant for all future struc tural applications in vehicles and aircrafts such as urban air vehicles, satellites, HAPS, NGWS/FCAS, drones or other carriers. Especially, load adapted 3D rein forced composite structures are generic enablers for loaded lightweight structures.

One possibility to achieve 3D reinforced composite structures is composite 3D printing of the whole reinforced composite part which is especially usable for a small-scale production. For a larger series production, manufacturing by thermo bending and overmoulding can be used with higher investments in manufacturing tools.

EP 3 231 592 A1 relates to a method for manufacturing a part made from compo site material, having a body and one or more continuous fibre bundles in its inte rior, characterised in that it comprises the stages of:

a) obtaining a body that includes one or more tubular cavities in its interior that ex tend between a first end, disposed on the outer surface of the body and which comprises an inlet orifice, and a second end, opposite to the first end; b) introduc ing resin in the liquid state and a continuous fibre bundle in the interior of at least one tubular cavity through its inlet orifice; and c) curing the resin until it solidifies, adhering to the body and fixing the continuous fibre bundle. EP 3 231 592 A1 also relates to a system for manufacturing a part made from composite material and to the part made from composite material obtained. The object of the invention is to enable manufacturing of more lightweight load adapted 3D reinforced composite material parts with lower tool and processing costs.

For achieving this object, the invention provides a manufacturing method, a manu facturing system and a composite material part obtainable therewith in accordance with the independent claims. Advantageous embodiments form the subject-matter of the dependent claims.

According to one aspect, the invention provides a manufacturing method for man ufacturing a part made of composite material with a continuous fibre reinforce ment, the method comprising the steps:

a) providing a body with tubular cavities and having at least one first portion made from a first polymer material and at least one second portion made from a second polymer material;

b) introducing resin and continuous fibres into the tubular cavities,

c) at least partially removing the second polymer material.

Step a) comprises:

a1 ) selecting the second polymer material from materials that are soluble in a solvent and the first polymer material from polymer materials that are non-soluble in said solvent.

Step c) comprises:

c1 ) dissolving the second material in the solvent.

Preferably, step c) comprises:

c2) removing the at least one second portion. Preferably, step c) comprises:

c3) removing all the second material from the body.

Preferably, step a) comprises:

a2) additive layer manufacturing of the body.

Preferably, step a) comprises:

a3) designing the body with first portions defining openings of the cavities. Preferably, step a) comprises:

a4) designing the body with first portions defining curvature portions of the cavi ties.

Preferably, step a) comprises:

a5) designing the body with first portions defining junction areas of the continu ous fibre reinforcement.

Preferably, step a) comprises:

a6) designing the body with the at least one second portion defining middle sec tions of the tubular cavities.

Preferably, step a) comprises:

a7) designing the body with the at least one second portion defining straight sec tions of the tubular cavities.

Preferably, step a) comprises:

a8) designing the body with a larger amount of second material and a smaller amount of first material. Preferably, at least 60% per weight, especially 70%-95% by weight, of the body are made from the second material.

Preferably, step a) comprises:

a9) designing the body with several first portions spaced apart from each other and connected by at least one second portion.

Preferably, step a) comprises:

a10) designing the body such that the at least one tubular cavity subsequently passes through the at least one first portion and the at least one second portion.

Preferably, step a) comprises:

a11 ) adding and/or connecting a metal member to the body such that the metal member has openings in alignment with open ends of the tubular cavities.

Preferably, step b) comprises:

b1 ) introducing the resin in a liquid state and a continuous fibre bundle simultane ously.

Preferably, step b) comprises:

b2) introducing a continuous fibre bundle within said at least one tubular cavity exerting on the continuous fibres a viscous drag force by means of a pressurized fluid or the resin, applying pressure differential.

Preferably, step b) comprises:

b3) introducing a continuous fibre bundle within said at least one tubular cavity exerting a mechanical pushing force on the bundle of continuous fibres.

Preferably, step b) comprises: b4) introducing the resin and the continuous fibres sequentially, especially first the continuous fibres and subsequently the resin in a liquid state.

Preferably, step b) comprises:

b5) introducing reinforcing fibres, especially carbon fibres and/or a carbon fibre bundle.

Preferably, step b) comprises:

b6) introducing functional fibres, especially glass fibres and/or ceramic fibres. Preferably, step b) comprises:

b7) introducing glass fibres for forming at least one thermal and/or strain gauge. Preferably, step b) comprises:

b8) introducing ceramic fibres for forming at least one actuator. Especially, by in troducing ceramic bundles for forming a fibre structure having piezoelectric proper ties, one or several piezoelectric actuators can be formed in the fibre structure.

Preferably, step b) comprises:

b9) curing the resin after introducing the resin and continuous fibres into the tub ular cavities.

According to a further aspect, the invention provides a composite material part, ob tainable by a manufacturing method according to any of the preceding embodi ments.

Preferably, the composite material part is formed as a reinforcement fibre truss structure. According to another aspect, the invention provides a manufacturing system for manufacturing a part made of composite material with a continuous fibre reinforce ment, comprising:

an additive layer manufacturing device for additive layer manufacturing a body having at least a first portion from a first material which is non-soluble in a solvent and a second portion from a second material which is soluble in the solvent and at least one tubular cavity passing through the first and second portions;

a resin and fibre introduction device for introducing resin and continuous fibres into the at least one tubular cavity; and

a dissolving device for dissolving the second material in the solvent.

According to another aspect, the invention provides a transport carrier or vehicle, especially a manned or unmanned aircraft or satellite, comprising a part obtained by a method according to any of the preceding embodiments and/or by using a manufacturing system according to the further aspect of the invention and/or a composite material part as described above.

The invention relates to the field of material science and especially to a manufac turing of 3D reinforced composite structures. Preferred use for such structures ob tainable by embodiments of the invention are structural applications in transport carriers and vehicles and aircrafts such as urban air vehicles, satellites, HAPS, NGWS/FCAS, drones. More generally, parts obtainable by the invention are used as basis for loaded lightweight structures.

Embodiments of the invention especially use a continuous fibre injection process such as disclosed and described in EP 3 231 592 A1 which is incorporated herein by reference. Embodiments of the invention provide full 3D fibre reinforcements which are seen as a missing brick for lightweight parts and that are not manufac turable up to date. Embodiments of the invention relate to a method for producing full 3d fibre rein forced polymer composite materials by means of 3d-printed soluble manufacturing tools.

The continuous fibre injection process has the advantage that 3D load adapted re inforced composite parts can be manufactured at low production costs with low in vestments in tools. Since fibres are injected with high pressure in tubular cavities in a polymer body, the body needs a polymer structure that can withstand these pressures. With the invention, it is possible to lower the weight of parts that are ob tained by such a continuous fibre injection process.

Preferred embodiments of the invention have at least one, several or all of the fol lowing advantages:

• It is possible to provide a carbon fibre UD (unidirectional) reinforcement with up to approximately 50x higher specific strength/modulus compared to high performance polymers including best resistance against creep, tempera ture/media, fatigue, etc.

• Loads in structures are oriented in full 3d - technics with full 3d fibre orienta tion capability needed.

• Beside load-carrying reinforcements, functional fibres can be integrated

(such as glass fibres as thermal/strain gauges, ceramic fibres as actuators).

• Preferred embodiments of the invention provide composite structures with low polymer ratio/mass, but ideal full 3d oriented reinforcement fibres with lowest tool and processing costs feasible.

• The manufacturing method is ideal for low/medium rate series.

Preferred embodiments of the manufacturing system comprise especially technical means for producing full 3d composite structures. According to a preferred embodiment a geometrical design of fibre reinforcement, polymer part material and soluble auxiliary/support material is provided.

The geometrical design is transferred into a process path (G-code), for example via s eer software.

The first material is especially a polymer part material (e.g. PEEK). The second material is especially a solvable support material (e.g. 3dGence ESM-10).

Preferably, liquid resin and reinforcement/functional fibres are provided.

Preferably, an ALM (Additive Layer Manufacturing) machine is used which is capa ble to process at minimum one part polymer material and one soluble material. Ex amples for such an ALM are FLM (Filament Layer Manufacturing) printers (availa ble on market), modified HSS machines (HSS = High Speed Sintering; e.g. Binder Jetting with IR activation with an adapted ink) or adapted SLS machines with multi material recoater (SLS = Selective Laser Sintering, especially feasible with two kind of materials, an example is the Aerosint re-coater, available from the com pany Aerosint).

Embodiments of the system further include a Fibre injection machine (CFIP) and, eventually, an oven - in case of hot curing thermoset resin. An example of a CFIP machine is shown and described in EP 3 231 592 A1 , incorporated herein by refer ence.

Embodiments of the system further provide a solvent to dissolve the support mate rial.

Preferred embodiments of the manufacturing method comprise the following steps: 1 ) Geometrical design of the fibre reinforcement, polymer part material (exam ple of the first material) and surrounding auxiliary/support material (example of the second material).

2) Generation of the process path with conventual s eer software e.g. Sim- plify3d, Cura, Slic3r, ...

3) Printing of the first and second materials in one step with fibre paths inte grated as open cavities, especially tubular cavities

4) Surface cleaning with subtractive processes (solvents, sandblasting milling, drilling, etc.) if needed

5) Injection of dry fibres with liquid resin in accordance with the CFIP process and device, e.g. as described and shown in EP 3 231 592 A1

6) Curing of thermoset resin in fibre reinforcements in oven if required

7) Dissolution of second material with subtractive technics and/or solvents (ac ids, water, etc.)

8) Finishing processes such as cutting fibre ends and/or cleaning of surface with sand-blasting, milling, grinding, solvents or others if needed.

According to preferred embodiments a full 3d reinforced part with local polymer and load oriented“naked” fibre reinforcements is achieved.

Preferred embodiments of the invention are described in more detail with refer ence to the accompanying drawings.

Fig. 1 a flow chart of a method for manufacturing a part made of composite material with a continuous fibre reinforcement;

Fig. 2 a perspective view of a body which is obtained in a first step of the man ufacturing method of Fig. 1 ;

Fig. 3 a perspective view of the body of Fig. 2; Fig. 4 a side view of the body of Fig. 2;

Fig. 5 a plan view of a metallic member which is optionally used in the method of Fig. 1 ;

Fig. 6 a perspective view of the metallic member of Fig. 5;

Fig. 7 a perspective view of the body of Fig. 2 with a metallic member of Fig. 5 attached thereto;

Fig. 8 a further perspective view of the arrangement of the body and the me tallic member of Fig. 7;

Fig. 9 a view similar to Fig. 7 after a further step of the manufacturing method wherein continuous fibres have been injected into the body;

Fig. 10 another perspective view of the arrangement of Fig. 9 with the body, the metallic member and the continuous fibres injected into the body;

Fig. 11 a perspective view of the part manufactured with the method of Fig. 1 with the optional metallic member;

Fig. 12 a further perspective view of the part of Fig. 11 ; and

Fig. 13 a side view of the part of Fig. 11

Fig. 1 is a flow chart for a manufacturing method for manufacturing a part 10 made of a composite material 12 with a continuous fibre reinforcement 14. An example for such a part 10 obtained or obtainable by such method is shown in Figs. 11 to 13.

The method comprises a first step:

51 providing a body 16 - see Fig. 2 to 4 - with tubular cavities 18 and with at least one first portion 20 made from a first polymer material 22 and at least one second portion 24 made from a second polymer material 26.

Further, the manufacturing method of Fig. 1 comprises a second step:

52 introducing resin and continuous fibres 28 - see Fig. 9 and 10 - into the tub ular cavities 18 of the body 16.

Further, the manufacturing method of Fig. 1 comprises a third step:

53 removing the at least one second portion 24.

In a preferred embodiment, the first step S1 comprises manufacturing of one or several tool parts containing tubular cavities 18 inside. Preferably, the second pol ymer material 26 is a soluble polymer which is soluble in a specific solvent, while the first polymer material 22 is a non-soluble polymer that is not soluble in the spe cific solvent. Most preferably, the body 16 is made by additive layer manufacturing with the non-soluble and soluble polymers 22, 26.

For manufacturing of the body 16, step S1 comprises a first sub-step:

S1 a geometrical design of the fibre reinforcement 14, of the first polymer material 22 which shall be present in the part to be manufactured and of the second poly mer material 26 which is only used as surrounding auxiliary or support material for the manufacturing of the part 10 and which is removed in step S3.

For example, the design is made with CAD software. In the first sub-step S1a, the body 16 is preferably designed such that each tubular cavity 18 passes through the body 16 from a first open end 30 to a second open end 32.

In a preferred embodiment, the first portions 20 are designed such that first por tions 20 are present in areas where the continuous fibres 28 - which are injected in the second step S2 in the form of fibre bundles 36 - form a curvature and/or in junction areas 40 of the part 10. In the junction areas 40, different fibre bundles 36 are close to each other. In the embodiment shown, the part 10 is a composite truss structure 42 with truss struts formed by the continuous fibre bundles 36 and truss nodes formed by the junction areas.

The at least one second portion 24 is present in all other areas of the body 16. Es pecially, the at least one second portion 24 forms the wall of the tubular cavities 18 in middle portions thereof and/or in straight sections thereof.

Most preferably, the tubular cavities 18 pass subsequently through a first portion 20 and a second portion 24. In preferred embodiments, at least one of the first and second open ends 30, 32 of a tubular cavity 18 is formed by a first portion 20.

Referring back to Fig. 1 , the first step S1 of the manufacturing method further com prises a second sub-step:

S1 b manufacturing the body 16 using an additive layer manufacturing ma chine (ALM machine - not shown).

Especially, the second sub-step S1 b comprises generating of a process path with conventional sheer software such as Simplify3d Cura, Slic3r, ... Especially, the de sign obtained by the first sub-step S1a is converted in a machine-readable form that can be read and processed by an additive layer manufacturing machine. As ALM machine, any ALM machine (also called 3D printer) can be used that is capable to process the first and second polymer materials 22, 26. The first and second polymer materials 22, 26 can be chosen as needed. In preferred embodi ments, the materials 22, 26 are chosen such that the first polymer material 22 is not soluble by a solvent and the second material 26 is soluble by the solvent. For example, the second polymer material 26 is a material which is available on the market as soluble auxiliary material for supporting a 3D structure during printing and that can be removed afterwards. One example is 3dGence ESM-10. The first polymer material 22 is a polymer material which can be printed and which is not soluble by the solvent which is used to remove the second polymer material 26. One example is PEEK. Further examples are PE, PP, ABS, PETG, ...

Examples for the ALM machine are a FLM printer (available on the market), HS machines or SLS machines.

One example for a result of the second sub-step S1 b is shown in Fig. 2 to 4. It shows the body 16 with the tubular cavities 18 having the first open end 30 and second open end 32 and a complex path there between, wherein the first portions 20 made of the first polymer materials 22 are present to form the second open end 32, junction points or junction areas 40 and/or curvature sections of the tubular cavities 18. In an embodiment not shown, additional first portions 20 can also form the first open ends 30. In the embodiment as shown in the Fig. 2 to 4, the first open ends 30 are provided within the second portion 24 which surrounds and con nects several first portions 20 arranged spaced apart from each other.

One aim of the design of the body is to achieve a part with a very low polymer to reinforcement fibre ratio. Hence, the second material 26 to be removed in the third step and used as auxiliary material only is preferably the dominant material in the body 16. For example, the 60% per weight, especially 70 to 95% per weight of the body is made from the second material 26, and only the rest is made from the first material. Hence, the part 10 will contain only 5 to 40 % of the polymer material of the body 16.

The body 16 is used as a tool to manufacture the part 10 which is shown in Fig. 11 to 13. The second portion 24 acts as a form for the tubular cavities 18 in order to inject the continuous fibres 28.

In the embodiment shown, it is further possible to add a third material, for exam ple, a metallic material. An example for a metallic member 44 is shown in Fig. 5 and 6. The metallic member 44 has, on one side, a form that is complementary to one end of the body 16, especially complementary to one end of the second por tion 24. The metallic member 44 has openings that can be aligned with the first open ends 30. The metallic member 44 can be attached to the end of the body 16 which has the first open ends 30 of the tubular cavities 18.

According to one example, the metallic member 44 has protruding portions 48 de fining the openings 46 that can be engaged with recessed portions 50 of the sec ond portion 24 defining the first open ends 30 of the tubular cavities 18.

Hence, referring back to Fig. 1 , the first step S1 can optionally have the additional sub-steps:

S1 c manufacturing a metallic member 44, and

S1 d pre-assembling the body 16 and the metallic member 44.

In the third sub-step S1 c, the metallic member 16 can, for example, be made by machining or other manufacturing technologies.

In one preferred embodiment of the fourth sub-step S1 d, the pre-assembling is done with coincident tubular cavities 18, i. e. the opening 46 are in alignment with the first open ends 30 of the tubular cavities 18. The assembly can be done by different technologies. For example, the metallic member 44 and the body 16 can be attached to each other by positive engagement between the protruding portions 48 and the recessed portions 50. The different parts of the manufacturing tool 52, for example, the body 16 and the metallic member 44, can also be connected to each other, for example by gluing or bonding.

Preferably, the manufacturing tool 52 is formed by an arrangement of the body 16 and a further member such as the metallic member 44 as shown in Fig. 7 and 8.

After the fourth sub-step S1 d of the first step S1 , the second step S2 is conducted. In the second step S2, a continuous fibre injection process (CFIP) is conducted such as this is described in EP 3 231 592 A1. Preferably, the fibres bundles 36 are injected together with a liquid resin into the tubular cavities 18. This process is generally known from EP 3 231 592 A1 and is not described further herein. Espe cially, carbon fibres are injected with a thermoset resin. The fibre bundles 36 are then formed by the path of the tubular cavities 18, i. e., the fibre bundles 36 take the form of complex paths of the tubular cavities 18. Then, the resin which is in jected together with the fibre bundles 36 is set so that the form of the fibre bundles 36 is fixed by the resin.

Thus, the manufacturing tool 52 is used as form to form the fibre reinforcement structure.

The form can be chosen such that the loads in the composite truss structure 42 are oriented as needed. cAji]

According to preferred embodiments, not only load carrying reinforcement by us ing carbon fibre bundles can be integrated, but also functional fibres. Flence, in at least one of the tubular cavities 18, functional fibres such as glass fibres that can be used to form a thermal and/or strain gauge or ceramic fibres that can be used to form an actuator are injected.

The second step S2 can also include a setting of the resin. For achieving this, the manufacturing tool 52 with the injected fibre bundles 36 as well as the resin can be put in an oven (not shown) for curing the thermosetting resin. After the second step S2 a structure shown in Fig. 9 and 10 is obtained.

Figs. 9 and 10 show the manufacturing tool 52 containing the injected fibre bun dles 36. This manufacturing tool 52 is then put into a bath (not shown) with the sol vent in order to remove the second polymer material 26 by dissolving it. Such a bath is an example for a dissolving device for dissolving the second material 26.

Flence, the dissolution of the second polymer material 26 using a specific solvent is one preferred embodiment of the third step S3. The third step S3 may also in clude other technologies to remove the second material such as subtractive tech nologies. Especially, the second polymer material 26 can be handled similar to a sacrificial material as known in the semi-conductor component manufacturing.

After removal of the second material 26, the part 10 is achieved as shown in Fig.

11 to 13. In this particular embodiment, the part 10 is formed as a composite truss structure 42 with the first polymer material 22 forming junction areas 40 and/or cur vature areas while the fibre bundle 36 is fixed by the resin function as truss struts.

As visible from Fig. 11 to 13, the metallic member 44 can be used as a fixation means to fix the composite truss structure 42 to other components.

Especially, the part 10 achieved with the manufacturing method of Fig. 1 can be used for lightweight structure parts of air carrier or space carriers or other vehicles, such as manned or unmanned aircrafts or satellites. In order to achieve a composite material part (10) with a fully load adapted 3D fi bre reinforcement with low costs for tools and process, the invention provides a manufacturing method for manufacturing a part (10) made of composite material (12) with a continuous fibre reinforcement (14), the method comprising the steps: a) providing a body (16) with tubular cavities (18) and having at least one first portion (20) made from a first polymer material (22) and at least one second por tion (24) made from a second polymer material (26);

b) introducing resin and continuous fibres (28) into the tubular cavities (18), c) removing at least a part of the second polymer material (26).

Reference sign list:

10 part

12 composite material

14 continuous fibre reinforcement

16 body

18 tubular cavity

20 first portion

22 first polymer material

24 second portion

26 second polymer material

28 continuous fibre

30 first open end

32 second open end

36 fibre bundle

40 junction area

42 composite truss structure

44 metallic member

46 openings

48 protruding portions

50 recessed portions

52 manufacturing tool (e.g. body 16 and metallic member 44) S1 Providing body with first and second portions, made from first and second materials, respectively

S1 a geometrically designing of fibre reinforcement and the first and second por tions

S1 b manufacturing the body using additive layer manufacturing S1 c manufacturing a metallic member

51 d preassembling different parts of the body or of the body and a further mem ber

52 Introducing resin and continuous fibres into tubular cavities of body

53 Removing the at least one second portion