An adaptive nozzle for 3d-printing continuous fibre composite material

Abstract

An adaptive nozzle (300) for 3D-printing continuous fibre composite material is disclosed. The adaptive nozzle comprises: an inlet for entry (304) of a continuous fibre composite material having a first cross-sectional shape, into the adaptive nozzle; an outlet (306) for exit of the continuous fibre composite material from the adaptive nozzle; and an adaptor for selectively adapting a shape of the adaptive nozzle to change a cross-sectional form of the continuous fibre composite material from the first cross-sectional shape to a second cross-sectional shape. An apparatus for 3D-printing continuous fibre composite material comprising the adaptive nozzle and a method of controlling an adaptive nozzle for 3D-printing continuous fibre composite material is also disclosed.

Description

[0001] An Adaptive Nozzle for 3D-Printing Continuous Fibre Composite Material

[0002] FIELD OF DISCLOSURE

[0003] The disclosure relates to an adaptive nozzle for 3D-printing continuous fibre composite material, an apparatus for 3D-printing continuous fibre composite material, comprising the adaptive nozzle, and a method of controlling an adaptive nozzle for 3D-printing continuous fibre composite material.

[0004] BACKGROUND

[0005] 3D-printing of pure thermoplastic round filament can be carried out through so-called active printing, in which extruders are used to push a melted filament through a conical nozzle to deposit the material on a print bed.

[0006] EP3117982B1 describes a 3D-printing system and process capable of extruding pure thermoplastic filament via active printing. The nozzle has a rectangular outlet with a variable width and fixed thickness, which can be adjusted according to the requirements of the printed object. However, this system is not compatible with existing commercial slicer software and needs a proprietary slicing package.

[0007] CN206106386U discloses a variable bore extrusion nozzle of a 3D-printer. The printing system has a vertically movable duct to support material down to the printing tip of the nozzle. The system supports active printing of thermoplastics and the cross-section of the nozzle is rectangular.

[0008] WO2021145818A1 discloses a 3D-printing method and apparatus with a variablegeometry nozzle. The system is designed for active printing of extruded polymer filament. The variable section of the nozzle is configured to change the dimensions of the feedstock material whilst keeping the geometry rectangular.

[0009] Fibre-reinforced composite materials (for example, having carbon fibres embedded in polymer material) are gaining interest. Both chopped and continuous fibres may improve a polymer-based part strength and other material properties. Generally speaking, a continuous fibre composite material is stronger than a chopped fibre composite material because the fibre continuity distributes the applied load.

[0010] 55717005-1 Active printing, as described in the above systems, is not suitable for the 3D-printing of continuous fibre composites. Instead, a method referred to as passive printing is required. In passive printing, fibre-reinforced polymer is pulled through the nozzle (hence the process can be referred to as pultrusion) and then deposited on the print bed. The fibres can be pre-impregnated with the polymer, or could be impregnated at different processing stages depending on particular design choices. The nozzle in passive printing usually has a flat tip.

[0011] Continuous fiber composites are printed passively using a flat-head nozzle and a rectangular cross-section tape. Techniques that have been developed to facilitate this process include automated tape placement (ATP), where a tape feedstock material is fused with a laser or a heating source and a compaction roller is used to consolidate the deposited material to enhance the quality of the print.

[0012] It is an aim of the present disclosure to provide an adaptive nozzle for 3D-printing of continuous fibre composite material.

[0013] SUMMARY

[0014] The applicant has determined that the use of continuous fibre-reinforced composite tape feedstock could be fast and effective for 3D printing (or ATP) of straight line features. This is illustrated in image 100a of Figure 1 (a) which shows good fibre alignment for a straight raster which has been printed using rectangular-shaped fibre-reinforced composite tape. However, tape feedstock results in poor print quality when printing bends of significant curvature using rectangular-cross-section fibre-reinforced composite tape, as shown in image 100b of Figure 1 (b). In particular, image 100b shows a 45 degree bend with high fibre separation at the interior of the bend.

[0015] On the contrary, when 3D printing a round or bent feature, using continuous fibre- reinforced composite filament with a round cross-section, an inferior fibre alignment is observed when printing straight lines but an improved print quality is observed when printing bends of significant curvature, when compared to the case of rectangular fibre- reinforced composite tape. This is illustrated in image 200a of Figure 2(a) which shows poor fibre alignment for a straight raster which has been printed using round fibre- reinforced composite filament and image 200b of Figure 2(b) which shows good fibre

[0016] 55717005-1 alignment for a curved raster which has been printed using round fibre-reinforced composite filament. In particular, image 200b shows a 45 degree bend with low fibre separation at the interior of the bend.

[0017] In view of the above, the applicant proposes a system for real-time adaptation of the shape of a continuous fibre composite material, during a pultrusion process, so as to selectively change the cross-section of the continuous fibre composite material to suit the shape of the feature being printed. In this way, good print quality can be maintained for both straight and curved features, and without compromising on print speed. Thus, a novel adaptive nozzle is proposed that may be configured for in-line transformation of, for example, a tape to a filament or vice versa, for 3D-printing of continuous fibre composites.

[0018] According to a first aspect of the present disclosure, there is provided an adaptive nozzle for 3D-printing continuous fibre composite material, the adaptive nozzle comprising: an inlet for entry of a continuous fibre composite material having a first cross- sectional shape, into the adaptive nozzle; an outlet for exit of the continuous fibre composite material from the adaptive nozzle; and an adaptor for selectively adapting a shape of the adaptive nozzle to change a cross-sectional form of the continuous fibre composite material from the first cross- sectional shape to a second cross-sectional shape.

[0019] Thus, the disclosure provides a mechanism for 3D-printing (which may also be referred to as additive manufacturing) using continuous fibre composite material, whereby the geometry of the material can be altered as it passes through the adaptive nozzle of the apparatus. Advantageously, the geometry may be adapted in real-time during a 3D- printing process. The 3D-printing process may comprise pultrusion of the continuous fibre composite material to transform the feedstock cross-section from, for example, rectangle to circle, before it is printed as a straight line or bend.

[0020] The cross-sectional geometry of the continuous fibre composite material may be altered based on a predicted topology to be printed so as to optimise the geometry for the nature of the topology, thus resulting in enhanced product properties and reduced printing time. For example, the adaptive nozzle may be adapted to selectively output a rounded cross-

[0021] 55717005-1 section (e.g. filament), suitable for printing curved traces, and a rectangular cross-section (e.g. tape), suitable for printing straight traces, so as to increase both printing speed and quality relative to using either one of these geometries exclusively.

[0022] Notably, the proposed adaptive nozzle may constitute the output nozzle of the apparatus. However, in other cases, the proposed adaptive nozzle may be provided upstream of an output nozzle of the apparatus. Thus, the proposed adaptive nozzle may be provided as an internal or external component of the 3D-printing apparatus.

[0023] The continuous fibre composite material may comprise continuous fibre reinforced resin, polymer or thermoplastic composite materials. The fibres may comprise carbon, glass, kevlar, metal, aramid etc. An example continuous fibre composite material may comprise continuous carbon fibre - polyether ether ketone (CCF-PEEK).

[0024] The first cross-sectional shape may be a polygon (e.g. a quadrilateral) and the second cross-sectional shape may be at least partially rounded or the first cross-sectional shape may be at least partially rounded and the second cross-sectional shape may be a polygon (e.g. a quadrilateral).

[0025] Although any polygon may be employed, quadrilateral shapes are commonly used in the industry. The quadrilateral may be substantially rectangular, square or any other foursided polygon.

[0026] When the cross-sectional shape is at least partially rounded it may be circular, elliptical, semi-circular, part-circular or it may comprise one or more curved edges.

[0027] The adaptor may be configured for selectively adapting the shape of the outlet to change the cross-sectional form of the continuous fibre composite material.

[0028] The adaptor may comprise a motor configured to move at least one component in order to change the cross-sectional form of the continuous fibre composite material as it passes through the adaptive nozzle.

[0029] 55717005-1 According to a second aspect of the present disclosure, there is provided an apparatus for 3D-printing continuous fibre composite material comprising an adaptive nozzle according to the first aspect.

[0030] The apparatus may comprise a controller configured to control the adaptor selectively adapt a shape of the adaptive nozzle to change a cross-sectional form of the continuous fibre composite material from the first cross-sectional shape to a second cross-sectional shape. The controller may be configured for real-time control of the adaptor during printing so as to ensure the continuous fibre composite material has a cross-sectional form best suited to a geometry to be printed.

[0031] The apparatus may be configured for pultrusion of the continuous fibre composite material during printing of the continuous fibre composite material.

[0032] The apparatus may comprise a compaction roller configured to apply pressure to the continuous fibre composite material when deposited on a printing surface. The compaction roller may advantageously aid consolidation of the continuous fibre composite material once deposited. In some cases, the compaction roller may be configured to be heated in order to aid consolidation of the continuous fibre composite material once deposited.

[0033] The apparatus may comprise a controller configured to move the compaction roller around the adaptive nozzle as a printing direction changes so as to remain downstream of the deposited continuous fibre composite material.

[0034] The apparatus may comprise one or more further adaptive nozzle according the first aspect, wherein the one or more further adaptive nozzles are arranged in series upstream of said adaptive nozzle, to selectively change a cross-sectional form of the continuous fibre composite material.

[0035] According to a third aspect of the present disclosure, there is provided a method of controlling a adaptive nozzle for 3D-printing continuous fibre composite material comprising: selectively adapting a shape of the adaptive nozzle to change a cross- sectional form of continuous fibre composite material passing through the adaptive nozzle, from a first cross-sectional shape to a second cross-sectional shape.

[0036] 55717005-1 The method may comprise selectively adapting the shape of the adaptive nozzle based on a geometry to be printed.

[0037] The method may comprise selectively adapting the shape of the adaptive nozzle so that the second cross-sectional shape is at least partially rounded when a curved feature is to be printed.

[0038] The method may comprise selectively adapting the shape of the adaptive nozzle so that the second cross-sectional shape is a polygon (e.g. a quadrilateral) when a straight feature is to be printed.

[0039] The method may comprise selectively opening the adaptive nozzle (e.g. to disengage the adaptive nozzle from the continuous fibre composite material) so that the second cross-sectional shape is the same as the first cross-sectional shape when no change to the shape of the continuous fibre composite material is required.

[0040] The method may comprise selectively engaging or disengaging the adaptive nozzle from the continuous fibre composite material depending on a predicted trajectory of the adaptive nozzle when printing.

[0041] In the method of the third aspect, the adaptive nozzle may be in accordance with the first aspect.

[0042] The disclosure is concerned with a novel adaptive printer nozzle that has the capability to transform the shape of a feed-stock composite material, in real-time during the printing process, and achieve optimum fast deposition rates for rapid manufacturing of continuous fibre reinforced composites. When automated, the adaptive nozzle can adapt the feed-stock to tape or filament, as per the geometry of the part to be printed, and function “in-line” during an entire 3D-printing process. Using this novel adaptive printer nozzle, the 3D printed composites may have superior mechanical performance, mitigating fibre breakage and misalignment and consequently achieving enhanced printability and accelerated production of complex composite parts.

[0043] 55717005-1 The solution presented may comprise carrying out in-line pultrusion, where a polygon (e.g. quadrilateral) cross-section tape is transformed into an at least partially rounded cross-section filament, whenever required as per geometry of the printed part. The adaptive nozzle may be installed in the processing pipeline either before the output nozzle or integrated into (i.e. constituting) the output nozzle of the apparatus. By actuating the adaptive nozzle, it is possible to change the shape of the composite material, for example, from rectangular to round or vice versa. Therefore, when straight lines need to be printed, the output material can have a polygon (e.g. quadrilateral) crosssection (e.g. leaving the geometry of the tape untouched for the output nozzle to directly deposit), or the adaptive nozzle will be actuated to result in a complete or partially circular cross-section filament, making it suitable for deposition at bends and curves. When the system is automated, the printer head will actuate an adaptive section in real time, according to the shape of the printing trace: straight = rectangular tape; curved = round filament. A compaction roller acting downstream of the adaptive nozzle and / or output nozzle may improve material consolidation, as soon as it is printed.

[0044] The method may use existing slicing software, which transforms a 3D model into a series of 2D layers to be printed on top of one another. This way, the geometry of each printed layer could be obtained. The aim of the method is not to change the pultrusion rate of the filament during printing, but rather to adapt the shape of the filament during printing. However, in some cases, the method might additionally be required to vary the speed of the pultrusion process. Hence, an accompanying software package may be required to link the geometry of the printing trace to the operation of the in-line adaptive nozzle (capable of changing tape / filament feedstock geometry) in terms of both the shape and the speed of the material flow through the in-line adaptive nozzle for the pultrusion process. Notably, the travel speed of the output nozzle for deposition of the material onto a surface can be independent of the speed of the pultrusion process.

[0045] At least some of the above and other features of the invention are set out in the claims.

[0046] These and other aspects will be apparent from the embodiments described in the following. The scope of the present disclosure is not intended to be limited by this summary nor to implementations that necessarily solve any or all of the disadvantages noted.

[0047] 55717005-1 Any features described in relation to one aspect of the disclosure may be applied to any one or more other aspect of the disclosure.

[0048] Brief Description of Certain Embodiments

[0049] Some embodiments of the disclosure will now be described by way of example only and with reference to the accompanying drawings, in which:

[0050] Figure 1 (a) shows a straight raster which has been printed using rectangular crosssection fibre-reinforced composite tape.

[0051] Figure 1 (b) shows a curved raster which has been printed using rectangular crosssection fibre-reinforced composite tape.

[0052] Figure 2(a) shows a straight raster which has been printed using round cross-section fibre-reinforced composite filament.

[0053] Figure 2(b) shows a curved raster which has been printed using round cross-section fibre-reinforced composite filament.

[0054] Figure 3(a) shows an illustration of an adaptive nozzle according to the present disclosure, when configured for printing a straight raster using rectangular cross-section fibre-reinforced composite tape as feedstock.

[0055] Figure 3(b) shows an illustration similar to that of Figure 3(a), when the adaptive nozzle is configured for printing a curved raster by adapting the shape of the feedstock into a round fibre-reinforced composite filament.

[0056] Figure 4 shows a flow diagram for 3D-printing using composite tape, according to the present disclosure.

[0057] Figure 5(a) shows an adaptive nozzle assembly according to the present disclosure.

[0058] Figure 5(b) a support bar for use in the adaptive nozzle assembly of Figure 5(a).

[0059] Figure 5(c) shows a dual hand threaded bar for use in the assembly of Figure 5(a).

[0060] Figure 6(a) shows a front view of the assembly of Figure 5(a) illustrating a passageway for the feedstock material to pass through the assembly.

[0061] Figure 6(b) shows a side view of the assembly of Figure 6(a) with an attached motor.

[0062] Figure 7(a) shows a perspective view of a tape to filament module of the assembly of Figure 5(a).

[0063] Figure 7(b) shows a perspective view of one half of the tape to filament module of Figure 7(a).

[0064] 55717005-1 Figure 8(a) shows a perspective view of a filament to tape module of the assembly of Figure 5(a).

[0065] Figure 8(b) shows a perspective view of one half of the filament to tape module of Figure 8(a).

[0066] Figure 9 shows a perspective view of the tape to filament module of Figure 7(a) when in a disengaged configuration to allow tape to pass through unaltered.

[0067] Figure 10 shows a side view of an apparatus for 3D-printing in accordance with the disclosure.

[0068] Detailed Description of the Preferred Embodiments

[0069] As illustrated in Figures 3(a) and 3(b), the disclosure proposes an adaptive nozzle 300 for 3D-printing continuous fibre composite material 302. The adaptive nozzle 300 comprises an inlet 304 for entry of a continuous fibre composite material 302 having a first cross-sectional shape, into the adaptive nozzle 300 and an outlet 306 for exit of the continuous fibre composite material 302 from the adaptive nozzle 300. An adapter 310 is provided between the inlet 304 and the output 306 for selectively adapting a shape of the adaptive nozzle 300 to change a cross-sectional form of the continuous fibre composite material 302 from the first cross-sectional shape to a second cross-sectional shape.

[0070] As shown in Figure 3(a), when the adapter 310 is disengaged from the continuous fibre composite material 302 no change to will be made to the cross-sectional shape of the continuous fibre composite material 302. Thus, the cross-sectional shape of the feedstock material will be maintained and printed by the adaptive nozzle 300. In the present example, the feedstock material is in the form of a rectangular cross-sectioned continuous fibre composite tape which is fed into the inlet 304, passed through the adapter 310 without change and then output from the outlet 306. As explained previously, the rectangular cross-sectioned continuous fibre composite tape is ideal for printing straight features 312.

[0071] As shown in Figure 3(b), when the adapter 310 is engaged with the continuous fibre composite material 302, the cross-sectional shape of the continuous fibre composite material 302 will be changed. Thus, the cross-sectional shape of the feedstock material may be altered and printed by the adaptive nozzle 300. In the present example, the

[0072] 55717005-1 feedstock material is in the form of a rectangular cross-sectioned continuous fibre composite tape which is fed into the inlet 304, passed through the adapter 310 to change the cross-section to a generally rounded filament 320 and then output from the outlet 306. As explained previously, the round cross-sectioned continuous fibre composite filament 320 is ideal for printing curved features 322.

[0073] Although not illustrated, in other examples, the feedstock material may be round crosssectioned continuous fibre composite filament and the adapter 310 may be configured to alter the cross-section of the filament to a rectangular cross-sectioned continuous fibre composite tape when engaged. In this example, disengagement of the adapter 310 would maintain the round cross-sectioned continuous fibre composite filament through the adaptive nozzle to output the same.

[0074] In either case, the adapter 310 may be controlled to selectively output a rectangular cross-sectioned continuous fibre composite tape for printing straight features 312 and a round cross-sectioned continuous fibre composite filament for printing curved features 322.

[0075] The first cross-sectional shape may be any polygon (e.g. a quadrilateral) and the second cross- sectional shape may be any partially rounded shape or the first cross-sectional shape may be any partially rounded shape and the second cross-sectional shape may be any polygon (e.g. a quadrilateral). For example, the quadrilateral may be substantially rectangular, square or any other four-sided polygon. When the cross-sectional shape is at least partially rounded it may be circular, elliptical, semi-circular, part-circular or it may comprise one or more curved edges.

[0076] Notably, the adapter 310 may be configured to alter one or both of the size and geometry of the feedstock material.

[0077] In the example shown, the continuous fibre composite material comprises a continuous carbon fibre reinforced thermoplastic composite material. The rectangular crosssectioned continuous fibre composite tape 302 may have a thickness of approximately 0.1mm and a width of approximately 1 mm. The rounded filament 320 may be circular with a corresponding diameter of approximately 0.4 to 0.6mm.

[0078] 55717005-1 Figure 4 shows a flow diagram 400 for 3D-printing using composite tape, according to the present disclosure. In a step 402, the 3D-printer is fed with continuous fibre composite tape as feedstock. In a step 404, the 3D-printer determines the raster geometry to be printed (e.g. according to standard slicing software). If the raster geometry is a straight path, the feedstock tape would be printed as it is fed and therefore the adapter of the adaptive nozzle described above would not be engaged. As such, in step 406, the tape would be printed. However, if, in step 404, the raster geometry is curved the adaptor 310 described above would be actuated in step 408 to convert the feedstock tape into a circular filament prior to printing in step 406. Thus, the 3D-printer has capability to effectively print straight and curved features using tape and filament, respectively, thereby ensuring optimum fibre alignment.

[0079] Figure 5(a) shows an adaptive nozzle assembly 500 according to the present disclosure. In this example, the adaptive nozzle assembly 500 comprises a housing 506 having a feedstock inlet 502 and a flat headed outlet 504. The feedstock inlet 502 has an external thread (not shown) for attaching the assembly 500 in a print head of a 3D-printer.

[0080] Within the housing 506 there is provided a first adapter 508 and a second adapter 510. As will be explained below, the first adapter 508 is configured to adapt a tape to a filament and the second adapter 510 is configured to adapt a filament to a tape. In some examples, only one adapter may be provided. In some examples, one or more further adapters may be provided to alter the cross-section to other shapes and / or sizes. In some examples the order of the first adapter 508 and the second adapter 510 may be reversed.

[0081] The housing 506 also supports a heat source 512 operable to heat at least a portion of the adaptive nozzle assembly 500 in order to make the composite material malleable for adapting the size and / or shape of the cross-section. A thermocouple sensor 514 is also provided for monitoring the temperature of the adaptive nozzle assembly 500.

[0082] In Figure 5(a) each of the first adapter 508 and second adapter 510 comprise two transverse bores 516 for accommodating tubular support bars 518 as shown in Figure 5(b).

[0083] 55717005-1 In addition, each of the first adapter 508 and second adapter 510 comprise a large threaded central transverse bore 520 for accommodating a dual hand threaded bar 522 as shown in Figure 5(c). The dual hand threaded bar 522 comprises a right-handed threaded portion 524 and a left-handed threaded portion 526 with a junction 528 therebetween.

[0084] As will be described in more detail below, each of the first adapter 508 and second adapter 510 comprise two halves which are connected by the support bars 518 and the dual hand threaded bar 522 such that rotation of the dual hand threaded bar 522 in one direction will pull the two halves together and rotation of the dual hand threaded bar 522 in the opposite direction will push the two halves apart.

[0085] Figure 6(a) shows a front view of the assembly 500 of Figure 5(a) illustrating a passageway 600 for the feedstock material to pass through the assembly 500. The passageway 600 pass from the inlet 502 to the outlet 504 via the first adaptor 508 and the second adapter 510. As illustrated, the passageway 600 is configured with a change of shape in the first adapter 508 so as to alter the cross-section of the feedstock from a tape to a filament. As shown, the passageway 600 in the second adapter 510 is in the form of an open cylinder so as to not alter the cross-section of the composite material any further. In other configurations, as will be explained below, the first adapter 508 may be configured to have an open passageway 600 to as to not alter the cross-section of the composite material passing there-through and the second adapter 510 may be configured such that the passageway 600 alters the cross-section of the feedstock from a filament to a tape.

[0086] Figure 6(b) shows a side view of the assembly 500 of Figure 6(a) with an attached motor 530. Collars 532 are provided in the housing 506 for supporting the support bars 518. A collar 534 is also provided for supporting the dual hand threaded bars 522 in each of the first and second adapters 508, 510. A driving portion 538 is connected to the motor 530 and configured for driving each of the dual hand threaded bars 522. Vertical grub screw holes 536 are provided through each of the first and second adapters 508, 510 for receiving grub screws (not shown) in order to hold the collars 532 on the support bars 518 and the collar 534 on dual hand threaded bar 522.

[0087] 55717005-1 In use, the motor 530 will be activated to drive the dual hand threaded bars 522 via the driving portion 538. In this example, each of the first and second adapters 508, 510 is provided an oppositely orientated dual hand threaded bar 522 such that rotation of the driving portion 538 will turn the dual hand threaded bar 522 of the first adaptor 508 in one direction and will turn the dual hand threaded bar 522 of the second adaptor 510 in the opposite direction. Thus, in this case, only one of the first and second adaptors 508, 510 will be engaged with the composite material in the passageway 600 whilst the other of the first and second adaptors 508, 510 will be disengaged. Changing the direction of the motor 530 will change the direction that the driving portion 538 is turned, which will result in the second adaptors 510 being engaged and the first adaptor 508 being disengaged. In other examples, the first and second adaptors 508, 510 may be separately engaged or disengaged from the composite material. In some cases, the first and second adaptors 508, 510 may be configured to be engaged at the same time.

[0088] Figure 7(a) shows a perspective view of a tape to filament module constituting the first adaptor 508 of the assembly 500 of Figure 5(a). The adapter 508 is comprised of two symmetric sections 508a and 508b arranged such that the passageway 600 is formed between them. In this case, the first adaptor 508 is configured to transform rectangular cross-sectioned continuous fibre composite tape 302 into rounded filament 320. This is achieved by the passageway 600 having an upper funnel portion 602 configured to transition of the rectangular cross-sectioned continuous fibre composite tape 302 passing therethrough into a depending tubular portion 604 for pultrusion of the tape 302 into the rounded filament 320.

[0089] Figure 7(b) shows a perspective view of one half 508a of the tape to filament module constituting the first adaptor 508 of Figure 7(a). This shows the transverse bores 516 for the support bars 518 and the threaded central transverse bore 520 for accommodating the dual hand threaded bar 522. The grub screws 536 for holding the collars 532 and 534 for supporting the support bars 518 and dual hand threaded bar 522, which extend through each of the two symmetric sections 508a and 508b, are also shown. More specifically, one of the two symmetric sections 508a and 508b has a right-handed taped bore 520 and the other of the two symmetric sections 508a and 508b has a left-handed taped bore 520. This, when the dual hand threaded bar 522 is rotated by the motor 530, the two symmetric sections 508a and 508b are simultaneously translated towards or away from each other by a single direction rotation, mimicking a screwjack.

[0090] 55717005-1 As shown in Figure 7(b), the rectangular cross-sectioned continuous fibre composite tape 302 is forced into a transition shape 700 while passing through the funnel portion 602 before exiting the adapter 508 in the form of a rounded filament 320.

[0091] Figure 8(a) shows a perspective view of a filament to tape module constituting the second adaptor 508 of the assembly 500 of Figure 5(a). The adapter 510 is comprised of two symmetric sections 510a and 510b arranged such that the passageway 600 is formed between them. In this case, the second adaptor 510 is configured to transform rounded filament 320 into rectangular cross-sectioned continuous fibre composite tape 302. This is achieved by the passageway 600 having an upper tubular portion 606 and a lower flattened funnel portion 608 configured to transition the rounded filament 320 into the rectangular cross-sectioned continuous fibre composite tape 302.

[0092] Figure 8(b) shows a perspective view of one half 510a of the filament to tape module constituting the second adaptor 510 of Figure 8(a). This shows the transverse bores 516 for the support bars 518 and the threaded central transverse bore 520 for accommodating the dual hand threaded bar 522. The grub screws 536 for holding the collars 532 and 534 for supporting the support bars 518 and the dual hand threaded bar 522, which extend through each of the two symmetric sections 510a and 510b, are also shown. More specifically, one of the two symmetric sections 510a and 510b has a right- handed taped bore 520 and the other of the two symmetric sections 510a and 510b has a left-handed taped bore 520. This, when the dual hand threaded bar 522 is rotated by the motor 530, the two symmetric sections 510a and 510b are simultaneously translated towards or away from each other by a single direction rotation, mimicking a screwjack.

[0093] As shown in Figure 8(b), the rounded filament 320 is forced into a transition shape 800 while passing through the flattened funnel portion 602 to form the rectangular crosssectioned continuous fibre composite tape 302 before exiting the adapter 510.

[0094] Figure 9 shows a perspective view of the tape to filament module constituting the first adaptor 508 of Figure 7(a) when in a disengaged configuration to allow tape 302 to pass through without transformation. Thus, tape feedstock will be printed as tape and filament feedstock will be printed as filament.

[0095] 55717005-1 Figure 10 shows a side view of an apparatus 900 for 3D-printing in accordance with the disclosure. The apparatus 900 is configured for pultrusion of a continuous fibre composite material. As illustrated, the apparatus 900 comprises a feed source of thermoplastic material 902, which is formed into a desired shape by rollers 904, and a fibre bundle source 906, which is guided over a guide pulley 908. The thermoplastic material 902 and the fibre bundle source 906 are both fed into a guide pipe 910 where they are heated by a heater 914 to form continuous fibre composite material. A heat sink 912 is also provided to dissipate heat from the heater 914.

[0096] Once the continuous fibre composite material has been formed, it is feed through the adaptive nozzle apparatus 500 as described above. A controller 918 is connected to the adaptive nozzle apparatus 500 to selectively control the first and second adaptors to adapt a shape of the adaptive nozzle 500 so as to change a cross-sectional form of the continuous fibre composite material from a first cross-sectional shape to a second cross- sectional shape. The controller 918 is configured for real-time control of the first and second adaptors during printing so as to ensure the continuous fibre composite material has a cross-sectional form best suited to a geometry to be printed.

[0097] The apparatus 900 may comprise one or more further adaptive nozzles or one or more further adaptors as described herein. In some cases, only a single adapter may be provided.

[0098] As shown in Figure 10, the adaptive nozzle apparatus 500 is provided upstream of a standard output nozzle 916. In other cases, the adaptive nozzle apparatus 500 may replace the standard output nozzle 916.

[0099] A compaction roller 920 is provided downstream of the output nozzle 916. The compaction roller 920 is configured to apply pressure to the continuous fibre composite material when deposited on a printing surface. The compaction roller 920 advantageously aids consolidation of the continuous fibre composite material once deposited. In some cases, the compaction roller 920 may be configured to be heated in order to aid consolidation of the continuous fibre composite material once deposited. A shown, the controller 918 is also connected to the compaction roller 920 and is configured to move the compaction roller 920 around the output nozzle 916 as a printing

[0100] 55717005-1 direction P changes so that the compaction roller 920 remains downstream of the deposited continuous fibre composite material.

[0101] In some cases, the adaptive nozzle apparatus 500 may be retro-fitted into an existing 3D-printer.

[0102] In some cases, the apparatus 900 is in the form of an in-line pultrusion system, where a square tape is pultruded to make a round filament, whenever required by the geometry of the part being printed. It is the in-line actuation of the adaptor in the printer head which determines whether the output material from the adaptive nozzle will have a quadrilateral cross-section (e.g. leaving the geometry of the tape untouched for the output nozzle to directly press and deposit), or will result in an at least partially rounded (e.g. circular) cross-section filament, making it suitable for deposition to form bends and curves.

[0103] When the system is automated, the printer head will actuate one or more adaptors as described herein, in real-time, according to the shape of the printing trace: straight = rectangular tape; curved = round filament.

[0104] The apparatus 900 may be configured to use existing slicing software, which transforms a 3D model into a series of 2D layers to be printed on top of one another, for effective printing of continuous fibre composite material. As such, the adaptive nozzle apparatus 500 can be readily integrated into passive printing hardware setups. The only additional requirement is a software package which will control the output nozzle speed and shape of the filament based on predicted trace geometry. Optionally, a compaction roller may be added to the passive printing hardware to effect the pultrusion process.

[0105] Aspects of the disclosure aim to mitigate the trade-off between using a round crosssection filament in fused deposition modelling (FDM), also known as the material extrusion additive manufacturing technique; and Automated Tape Placement (ATP) using rectangular cross-section tape.

[0106] These two distinct 3D printing / additive manufacturing techniques have unique benefits. Using the round filament, it is possible to print complex shapes including bends and curves. However, the process is slow (having a deposition rate of ~3 mm / s) and the quality of long straight-line prints is not satisfactory for continuous fibre reinforced polymer composite materials. On the other hand, ATP can be rapidly deposited (having

[0107] 55717005-1 a deposition rate of >25 mm / s) along straight lines, but it suffers from fibre breakage / folding at curves and bends. The proposed invention comprises an adaptive nozzle design which may be configured to alternate between both printing methods, which is likely to result in enhanced product quality and reduced printing time.

[0108] The skilled person will understand that in the preceding description and appended claims, positional terms such as ‘above’, ‘along’, ‘side’, etc. are made with reference to conceptual illustrations, such as those shown in the appended drawings. These terms are used for ease of reference but are not intended to be of limiting nature. These terms are therefore to be understood as referring to an object when in an orientation as shown in the accompanying drawings.

[0109] Although the disclosure has been described in terms of particular embodiments as set forth above, it should be understood that these embodiments are illustrative only and that the claims are not limited to those embodiments. Those skilled in the art will be able to make modifications and alternatives in view of the disclosure which are contemplated as falling within the scope of the appended claims. Each feature disclosed or illustrated in the present specification may be incorporated in any embodiments, whether alone or in any appropriate combination with any other feature disclosed or illustrated herein.

[0110] 55717005-1

Claims

CLAIMS:

1. An adaptive nozzle for 3D-printing continuous fibre composite material, the adaptive nozzle comprising: an inlet for entry of a continuous fibre composite material having a first cross-sectional shape, into the adaptive nozzle; an outlet for exit of the continuous fibre composite material from the adaptive nozzle; and an adaptor for selectively adapting a shape of the adaptive nozzle to change a cross-sectional form of the continuous fibre composite material from the first cross-sectional shape to a second cross-sectional shape.

2. The adaptive nozzle of claim 1 wherein the first cross-sectional shape is a polygon and the second cross-sectional shape is at least partially rounded or the first cross-sectional shape is at least partially rounded and the second cross- sectional shape is a polygon.

3. The adaptive nozzle of claim 1 or 2 wherein the adaptor is configured for selectively adapting the shape of the outlet to change the cross-sectional form of the continuous fibre composite material.

4. The adaptive nozzle of any preceding claim wherein the adaptor comprises a motor configured to move at least one component in order to change the cross- sectional form of the continuous fibre composite material as it passes through the adaptive nozzle.

5. An apparatus for 3D-printing continuous fibre composite material comprising: an adaptive nozzle according to any preceding claim.

6. The apparatus of claim 5 configured for pultrusion of the continuous fibre composite material during printing of the continuous fibre composite material.

7. The apparatus of claim 5 or 6 comprising a compaction roller configured to apply pressure to the continuous fibre composite material when deposited on a printing surface.55717005-18. The apparatus of claim 7 comprising a controller configured to move the compaction roller around the adaptive nozzle as a printing direction changes so as to remain downstream of the deposited continuous fibre composite material.

9. The apparatus of any of claims 5 to 8 comprising one or more further adaptive nozzles according to any of claims 1 to 4, wherein the one or more further adaptive nozzles are arranged in series upstream of said adaptive nozzle, to selectively change a cross-sectional form of the continuous fibre composite material.

10. A method of controlling an adaptive nozzle for 3D-printing continuous fibre composite material comprising: selectively adapting a shape of the adaptive nozzle to change a cross- sectional form of continuous fibre composite material passing through the adaptive nozzle, from a first cross-sectional shape to a second cross- sectional shape.11 . The method of claim 10 comprising selectively adapting the shape of the adaptive nozzle based on a geometry to be printed.

12. The method of claim 10 or 11 comprising selectively adapting the shape of the adaptive nozzle so that the second cross-sectional shape is at least partially rounded when a curved feature is to be printed.

13. The method of any of claims 10 to 12 comprising selectively adapting the shape of the adaptive nozzle so that the second cross-sectional shape is a polygon when a straight feature is to be printed.

14. The method of any of claims 10 to 13 comprising selectively opening the adaptive nozzle so that the second cross-sectional shape is the same as the first cross- sectional shape when no change to the shape of the continuous fibre composite material is required.55717005-115. The method of any of claims 10 to 14 wherein the adaptive nozzle is in accordance with any of claims 1 to 4.55717005-1

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