Extruder system for 3D printing

Abstract

There is provided an extruder system (2) for a fused granulate fabrication 3D printer system, the extruder system (2) comprising: a feeding element (4) configured to receive fusible material; a barrel (10) coupled to the feeding element (4), the barrel (10) including a nozzle (50); and an extrusion screw (18) coupled to the feeding element (4), the extrusion screw (18) being housed inside the barrel (10) and being operable to, in use, drive the fusible material from the feeding element (4) to the nozzle (50), wherein at least one of the barrel (10) and the extrusion screw (18) is configured to be releasably coupled to the feeding element (4).

Description

[0001] EXTRUDER SYSTEM FOR 3D PRINTING

[0002] The invention relates to an extruder system for a fused granulate fabrication 3D printer system and to a 3D printer system comprising such an extruder system.

[0003] It is known that different materials require different flow rates for optimal 3D printing. In the case of fused granulate fabrication 3D printer systems, the rotation speed and the extrusion screw geometry affect the flow rates that can be provided by extruder systems. Extruder systems are therefore configured for use with materials having specific material properties.

[0004] According to a first aspect of the invention, there is provided an extruder system (e.g. an extruder head) for a fused granulate fabrication 3D printer system, the extruder system comprising: a feeding element configured to receive fusible material; a barrel coupled to the feeding element, the barrel including a nozzle; and an extrusion screw coupled to the feeding element, the extrusion screw being housed inside the barrel and being operable to, in use, drive the fusible material from the feeding element to the nozzle, wherein at least one of the barrel and the extrusion screw is configured to be releasably coupled to the feeding element.

[0005] The ability to releasably decouple the barrel and / or the extrusion screw from the feeding element not only enables the extruder system to quickly and easily switch between materials with minimised waste but also enables easier cleaning, simpler assembly and simpler maintenance of the extruder system. This avoids the need to completely disassemble the entire extruder system, which affects the precision of the 3D printer system that would have required re-calibration after the barrel and / or the extrusion screw are recoupled to the feeding element. In addition, this ability may be used to provide the 3D printer system with multi-material printing capability using a single extruder system (or a minimal number of extruder systems), as opposed to using a large number of extruder systems for different materials and / or different extrusion properties which increases the size, footprint and cost of the 3D printer system. Thus, the extruder system is particularly useful for use in desktop-sized 3D printer systems.

[0006] In a preferred embodiment of the invention, the extruder system may further include at least one replacement extrusion screw, wherein the or each replacement extrusion screw is releasably couplable to the feeding element. This enables an easy changeover from one extrusion screw to another extrusion screw.

[0007] In embodiments of the invention, the extrusion screw and the or each replacement extrusion screw may be shaped and / or sized differently to respectively set different extrusion flow rates of the extruder system. Exemplary shapes and / or sizes of the extrusion screw and the or each replacement extrusion screw are provided throughout the specification. The ease of changeover between extrusion screws enables the use of different extrusion flow rates of the extruder system, without having to disassemble the entire extruder system which can be disadvantageous for reasons already mentioned above.

[0008] In embodiments of the invention, the extrusion screw and the or each replacement extrusion screw may have different length to diameter (L / D) ratios. The length to diameter (L / D) ratios may be equal to or smaller than 6: 1. The length to diameter (L / D) ratios may be equal to or greater than 4.25: 1. In other embodiments of the invention, the length to diameter (L / D) ratios may be greater than 6: 1 or may be smaller than 4.25: 1.

[0009] In embodiments of the invention, the extrusion screw and the or each replacement extrusion screw may have different diameters.

[0010] In embodiments of the invention, the feeding element may comprise a screw drive coupler, and the extrusion screw may be releasably connectable to the screw drive coupler, preferably via a quick-release attachment element.

[0011] In further embodiments of the invention, the extruder system may further include at least one replacement barrel, the or each replacement barrel including a nozzle, wherein the or each replacement barrel may be releasably couplable to the feeding element. This enables an easy changeover from one barrel to another barrel.

[0012] In embodiments of the invention, the barrel and the or each replacement barrel may be shaped and / or sized differently to respectively set different extrusion flow rates of the extruder system. Exemplary shapes and / or sizes of the barrel and the or each replacement barrel are provided throughout the specification. The ease of changeover between barrels enables the use of different extrusion flow rates of the extruder system, without having to disassemble the entire extruder system which can be disadvantageous for reasons already mentioned above. In embodiments of the invention, the barrel and the or each replacement barrel may be shaped and / or sized to respectively house the corresponding extrusion screw and the or each corresponding replacement extrusion screw.

[0013] In embodiments of the invention, the barrel and / or the extrusion screw may be releasably coupled to the feeding element via a fastening member.

[0014] In further embodiments of the invention, the extruder system may comprise a heating element arranged around the barrel, the heating element operable to heat up the barrel. Preferably the heating element is operable to heat up the barrel up to 450°C.

[0015] In embodiments of the invention, the barrel may comprise at least two barrel parts, the at least two barrel parts being releasably couplable to each other.

[0016] In further embodiments of the invention, the barrel may include a barrel body, wherein the nozzle may be releasably coupled to the barrel body. The extruder system may further include at least one replacement nozzle, wherein the or each replacement nozzle may be releasably couplable to the barrel body. This enables an easy changeover from one nozzle to another nozzle. The nozzle and the or each replacement nozzle may be shaped and / or sized differently to respectively set different extrusion flow rates of the extruder system. Exemplary shapes and / or sizes of the nozzle and the or each replacement nozzle are provided throughout the specification. The ease of changeover between nozzles enables the use of different extrusion flow rates of the extruder system, without having to disassemble the entire extruder system which can be disadvantageous for reasons already mentioned above.

[0017] In embodiments of the invention, the nozzle and the or each replacement nozzle may have different internal nozzle angles. The internal nozzle angles may range between 30° and 180°.

[0018] In embodiments of the invention, the nozzle and the or each replacement nozzle may be shaped and / or sized to be respectively releasably couplable to the barrel body of the corresponding barrel and the or each corresponding replacement barrel.

[0019] In embodiments of the invention, the nozzle and the or each replacement nozzle may be respectively releasably couplable to the barrel body of the corresponding barrel and the or each replacement barrel via a fastening member. In further embodiments of the invention, the nozzle may comprise a flange defining a lip that projects away from an outlet orifice of the nozzle, the lip being configured to abut an extruding end of the barrel body.

[0020] In embodiments of the invention, the feeding element may be pivotable in a vertical plane to change an axial orientation of the barrel and extrusion screw relative to a horizontal plane.

[0021] According to a second aspect of the invention, there is provided an extruder system for a fused granulate fabrication 3D printer system, the extruder system comprising: a feeding element configured to receive fusible material; a barrel coupled to the feeding element, the barrel including a barrel body and a nozzle, wherein the nozzle is releasably coupled to the barrel body; and an extrusion screw coupled to the feeding element, the extrusion screw being housed inside the barrel and being operable to, in use, drive the fusible material from the feeding element to the nozzle, wherein the extruder system further includes at least one replacement nozzle, wherein the or each replacement nozzle is releasably couplable to the barrel body, wherein the nozzle and the or each replacement nozzle are shaped and / or sized differently to respectively set different extrusion flow rates of the extruder system.

[0022] The features and advantages of the first aspect of the invention and its embodiments apply mutatis mutandis to the second aspect of the invention and its embodiments.

[0023] In embodiments of the invention, the nozzle and the or each replacement nozzle may have different internal nozzle angles, the internal nozzle angles ranging between 30° and 180°.

[0024] In embodiments of the invention, the nozzle may comprise a flange defining a lip that projects away from an outlet orifice of the nozzle, the lip being configured to abut an extruding end of the barrel body.

[0025] In embodiments of the invention, the nozzle and the or each replacement nozzle may be respectively releasably couplable to the barrel body of the corresponding barrel and the or each replacement barrel via a fastening member. The fastening member may be configured to abut a flange of the nozzle and secure the lip of the nozzle against the barrel body. In embodiments of the invention, the feeding element may be additionally configured as a cooling element, preferably a fluid-cooled cooling element (e.g. a liquid-cooled cooling element or a gas-cooled cooling element). The coupling of the barrel and the extrusion screw to the cooling element (such as a cooling block) advantageously provides a compact arrangement that provides effective cooling of the barrel and the extrusion screw.

[0026] According to a third aspect of the invention, there is provided a 3D printer system comprising the extruder system according to any one of the preceding aspects and embodiments of the invention.

[0027] The features and advantages of the first and second aspects of the invention and their embodiments apply mutatis mutandis to the third aspect of the invention and its embodiments.

[0028] It will be appreciated that the use of the terms "first" and "second", and the like, in this patent specification is merely intended to help distinguish between similar features and is not intended to indicate the relative importance of one feature over another feature, unless otherwise specified.

[0029] Within the scope of this patent application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, and the claims and / or the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and all features of any embodiment can be combined in any way and / or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and / or incorporate any feature of any other claim although not originally claimed in that manner.

[0030] Preferred embodiments of the invention will now be described, by way of non-limiting examples, with reference to the accompanying drawings in which :

[0031] Figure 1 shows a perspective view of an extruder system according to an embodiment of the invention;

[0032] Figure 2 shows a cross-sectional view of the extruder system of Figure 1;

[0033] Figures 3a-3c show additional views of the extruder system of Figure 1; Figures 4a-4d show extrusion screws that are differently shaped to respectively set different extrusion flow rates;

[0034] Figure 5 shows an exploded view of parts of the extruder system of Figure 1;

[0035] Figures 6a and 6b show a pivotable extruder system in a first position and a second position respectively;

[0036] Figure 7 shows a partially exploded view of the barrel body and nozzle of Figure 1;

[0037] Figure 8a shows a perspective view of the nozzle of Figure 7;

[0038] Figure 8b shows a cross-sectional view of the nozzle of Figure 7;

[0039] Figure 8c shows a variation of the nozzle of Figure 8b;

[0040] Figure 8d shows a perspective view of another variation of the nozzle of Figure 7;

[0041] Figure 8e shows a cross-sectional view of the nozzle of Figure 8d;

[0042] Figures 9a-9b show an extruder system according to another embodiment of the invention;

[0043] Figure 10 shows a 3D printer system according to another embodiment of the invention; and

[0044] Figure 11 shows a perspective exploded view of a build platform that is part of the 3D printer system of Figure 10; and

[0045] Figure 12 shows a kinematic coupling of the 3D printer system of Figure 10.

[0046] The figures are not necessarily to scale, and certain features and certain views of the figures may be shown exaggerated in scale or in schematic form in the interests of clarity and conciseness.

[0047] An extruder system is described with reference to Figure 1 and is designated generally by the reference numeral 2. The extruder system 2 is for use in a 3D printer system.

[0048] The extruder system 2 comprises a feeding and cooling element 4, which may be in the form of a feeding and cooling block. The feeding and cooling block 4 comprises an attachment structure 6 for enabling the feeding and cooling block 4 to be mounted onto a movement rail (e.g. a gantry) of the 3D printer system.

[0049] The feeding and cooling block 4 is configured to receive fusible material which is capable of being melted and extruded. The feeding and cooling block 4 comprises a funnel 8 for receiving the fusible material. In this way the fusible material is gravity- fed into the feeding and cooling block 4. It will be understood that in other embodiments the fusible material may be received differently such as by way of a tube or container.

[0050] The fusible material preferably comprises pellets, granules, flakes, shreds, particulates or agglomerates, which may be of, but are not limited to, a size ranging between 2 and 7 mm. The fusible material may be a virgin raw material or a reprocessed material. The fusible material may include a regrind polymer or a composite mixture. The extruder system may be configured to receive fusible material of varying forms, shapes and sizes.

[0051] The fusible material may be any suitable material such as, for example, any one of acrylonitrile butadiene styrene (ABS), styrene acrylonitrile resin (SAN), polypropylene (PP), thermoplastic polyolefin (TPO), thermoplastic polyurethane (TPU), glass-filled polymer (GF), polylactide (PLA), cyclic olefin copolymer (COC), polycarbonate (PC), polyetherimide (PEI), polyetheretherketone (PEEK) or a combination thereof. Other polymers as the fusible material are envisaged.

[0052] The extruder system 2 further comprises a barrel 10 that is releasably coupled to the feeding and cooling block 4. The extruder system 2 further comprises a heating element 12 and a temperature sensor 14 arranged on the barrel 10. The feeding and cooling block 4 is preferably made of aluminium. The feeding and cooling block 4 comprises cooling channels 16 that are configured to receive a cooling fluid e.g. a fluid, preferably water.

[0053] In other embodiments, the extruder system may comprise a connecting block configured to releasably or fixedly connect to the various components of the invention. In further other embodiments, the components of the extruder system may be cooled by an external cooling arrangement such as a cooling sleeve releasably couplable to the barrel.

[0054] The extruder system 2 is shown in more detail in Figure 2. The extruder system 2 comprises an extrusion screw 18 that is releasably coupled to the feeding and cooling block 4 and housed inside the barrel 10. The extrusion screw 18 comprises a screw connecting portion 20, which is configured to be releasably coupled to the feeding and cooling block 4, and a screw extruding portion 22.

[0055] The feeding and cooling block 4 comprises a screw drive coupler 24 configured to receive the screw connecting portion 20 and, in use, drive it rotationally to create a flow of fusible material through the extrusion screw 18. The screw drive coupler 24 is connected to a motor (not shown). The motor may be capable of driving the screw connecting portion 20 at different rotational speeds to create a flow of fusible material through the extrusion screw 18 at different extrusion flow rates. In other embodiments the motor may be replaced by a different type of drive device. It is envisaged that the motor or other drive device may include a gear box or a gear reduction system.

[0056] The releasable coupling established between the screw connecting portion 20 and the feeding and cooling block 4 is shown in more detail in Figure 3a. Bearings 28 are located inside a bearing seat inside the feeding and cooling block 4. Precision machining of the bearing seat inside the feeding and cooling block 4 ensures that the bearings 28 are constrained in the correct position inside the bearing seat. A different number of bearings 28 may be used.

[0057] The screw connecting portion 20 comprises a flange 26 that is arranged to matingly abut the bearings 28 when part of the screw connecting portion 20 is arranged to extend through the bearings 28. The mating surfaces of the flange 26 and the bearings 28 are precision-machined to ensure excellent contact between the two surfaces. This helps to locate the extrusion screw 18 in the correct axial position, thus providing the correct alignment between the extrusion screw 18 and the barrel 10.

[0058] The screw connecting portion 20 is retained in the feeding and cooling block 4 by a quick-release attachment element 30. The quick-release attachment element 30 engages and locates the part of the screw connecting portion 20 extending past the bearings 28 in order to prevent the extrusion screw 18 from axially moving relative to the feeding and cooling block 4. The quick-release attachment element 30 is preferably an e-clip but in other embodiments may be a c-clip or any other suitable fastening member.

[0059] The part of the screw connecting portion 20 extending past the bearings 28 is received by the screw drive coupler 24 to enable rotational drive of the extrusion screw 18.

[0060] Once the quick-release attachment element 30 is removed, a tool 31 (e.g. a spanner) may be used to push the part of the screw connecting portion 20 extending past the bearings 28 in order to release the barrel 10 and lever out the extrusion screw 18, especially in the case of stiff material around the extrusion screw 18. Such use of the tool 31 is depicted in Figure 3c. The same tool 32 may be used to untighten the fastening member 53. Turning to Figures 4a-4d, the extruder system 2 additionally comprises one or more replacement extrusion screws 32,34,36,38, each of which is releasably couplable to the feeding and cooling block 4. The extrusion screw 18 and the replacement extrusion screw(s) 32,34,36,38 are shaped and sized differently to respectively set different extrusion flow rates of the extruder system 2.

[0061] The expression "flow rate" will be understood to generally refer to the melt flow rate (MFR) or the melt volume flow rate (MVR) of the fusible material. The flow rate of a polymer at its processing temperature has a great effect on the results achieved during 3D printing.

[0062] Figures 4a-4d show examples of various replacement extrusion screws 32,34,36,38 that are configured to be used for materials that require different flow rates. Figures 4a-4d respectively show an extrusion screw 32 for high flow rate applications, an extrusion screw 34 for medium-high flow rate applications, an extrusion screw 36 for medium-low flow rate applications and an extrusion screw 38 for low flow rate applications.

[0063] The extrusion screws 32,34,36,38 vary with regards to multiple parameters including the diameter, the helix angle, the channel depth, the compression ratio and the ratio of their length to diameter (L / D ratio). Non-limiting parameters for extrusion screws configured for different flow rates according to preferred embodiments are set out in the following table.

[0064] In use, each extrusion screw 32,34,36,38 comprises a solid feeding zone 40 with a constant root diameter, a transition zone 42 with a tapered root diameter, and a metering zone 44 with a constant root diameter, as exemplified in Figure 4d. The solid feeding zone 40 may be configured to span approximately half of the screw extruding portion 22 of the extrusion screw 18. Pressure is generated in the solid feeding zone 40 because the fusible material is still solid in this zone. The transition zone 42 is configured to be relatively short compared to the other zones to limit the melting of the fusible material to the distal portion of the extrusion screw 18, where compression is required.

[0065] The provision of replacement extrusion screws 32,34,36,38 releasably couplable to the feeding and cooling block 4 allows optimisation of the extruder system 2 for multiple materials without having to replace the whole extruder system 2 or having to use a different 3D printing system. Moreover, the L / D ratio of the extrusion screws 18,32,34,36,38 being equal or smaller than 6: 1 makes the extruder system 2 particularly suitable for desktop-sized 3D printers.

[0066] Referring back to Figure 2, the barrel 10 is releasably coupled to the feeding and cooling block 4 at a barrel connecting portion 46. More specifically, the barrel 10 includes a barrel body 48 that is releasably coupled to the feeding and cooling block 4, and includes a nozzle 50 that is releasably coupled to the barrel body 48 (as also shown in Figure 3b). The barrel body 48 extends in a longitudinal direction to house the extrusion screw 18 and defines an extruding end to which the nozzle 50 is releasably coupled via a fastening member 52. The heating element 12 is a coil arranged around the extruding end of the barrel body 48 to melt the fusible material in the space between the barrel 10 and the extrusion screw 18. The temperature sensor 14 is arranged around the extruding end of the barrel body 48 where the metering zone 44 is located.

[0067] In other embodiments of the invention, the barrel may comprise a nozzle that is integrally formed with the barrel body.

[0068] Turning to Figure 5, a partially exploded view of the extruder system 2 shows the barrel 10 in more detail. The feeding and cooling block 4 has an opening through which a portion 46 of the barrel body 48 is received. A connecting protrusion 54 is formed around the opening and on an outer surface of the feeding and cooling block 4.

[0069] The barrel 10 comprises a flange 56 that is formed at an intermediate position along the axial length of the barrel body 48. When the portion 46 of the barrel body 48 is received through the opening in the feeding and cooling block 4, the flange 56 abuts the connecting protrusion 54 to axially locate the barrel 10 with respect to the feeding and cooling block 4. Furthermore, the flange 56 has a pair of flat sides that flank tabs 58 that project from the connecting protrusion 54 of the feeding and cooling block 4. When the portion 46 of the barrel body 48 is received through the opening in the feeding and cooling block 4, the flat sides and the tabs 58 act to rotationally locate the barrel 10 with respect to the feeding and cooling block 4. Thus, the provision of the flange 56 limits the insertion of the barrel body 48 into the feeding and cooling block 4 while the cooperation of the flat sides and the two tabs 58 restricts the rotational movement of the barrel 10 relative to the feeding and cooling block 4.

[0070] The connecting protrusion 54 of the feeding and cooling block 4 comprises a threaded exterior surface. A fastening member 53 is configured to secure the barrel body 48 to the connecting protrusion 54 by abutting the flange 56 and screwing onto the threaded exterior surface. In a preferred embodiment the fastening member 53 is a nut, such as a c-nut.

[0071] In alternative embodiments the coupling of the barrel body and the feeding and cooling element may be varied without departing from the scope of the invention. For example the barrel flange may have alternative shapes, and the connecting protrusion may comprise no tabs or a larger number of tabs.

[0072] The extruder system 2 additionally comprises one or more replacement barrels that are releasably couplable to the feeding and cooling block 4. The barrel 10 and the replacement barrel(s) are shaped and / or sized differently to respectively set different extrusion flow rates of the extruder system 2.

[0073] Preferably each of the barrel 10 and the replacement barrel(s) is specifically designed for a respective one of the extrusion screw 18 and replacement extrusion screw(s) 32,34,36,38. Specifically, the barrel 10 and the replacement barrel(s) are shaped and / or sized to respectively house a corresponding extrusion screw 18 or corresponding replacement extrusion screw 32,34,36,38. This is because different extrusion screws may have different dimensions that require different barrels to house them in order for the feeding and cooling block 4 to function optimally. The or each replacement barrel(s) may be identical to the barrel 10 with the exception of having a different internal diameter and / or length. The or each replacement barrel(s) may be releasably couplable to the feeding and cooling block 4 using a fastening member, which may be the same fastening member 53 or a different fastening member. In other embodiments, the barrel and / or the replacement barrel(s) may comprise at least two barrel parts, the at least two barrel parts being releasably couplable to each other. More specifically, the barrel body of the barrel may comprise two barrel parts that are releasably couplable to each other along the longitudinal axis of the barrel. The two barrel parts may be secured to each other during operation of the extruder system via a fastening member such as a clamp or a nut.

[0074] The attachment structure 6 of Figures 1 and 2 provides a fixed connection between the feeding and cooling block 4 and a movement rail of the 3D printer system. However, the attachment structure may be configured to provide an adjustable connection. Figures 6a and 6b show an extruder system 60 according to an embodiment of the invention that is substantially identical to the extruder system 2 of Figure 1 with the exception that it comprises an adjustable attachment structure 62. The adjustable attachment structure 62 allows for the pivotable movement of the feeding and cooling block 4. The adjustable attachment structure 62 enables the pivotable movement of the feeding and cooling block 4 in a vertical plane to change an axial orientation of the barrel 10 and extrusion screw 18 relative to a horizontal plane, i.e. rotating about the X or Y axes. The adjustable attachment structure may comprise any suitable coupling means for achieving this adjustable connection such as a hinge, an articulated joint or a ratchet mechanism.

[0075] Figure 6a shows the feeding and cooling block 4 in a first position and Figure 6b shows the feeding and cooling block 4 in a second position following a pivot movement. The first position could be a printing position. The second position could be a cleaning or maintenance position. The feeding and cooling block 4 in the second position allows for more space to remove the barrel 10 and the extrusion screw 18 of the extruder system 60 relative to the first position. This improves access to the barrel 10 and the extrusion screw 18 without having to necessarily increase the overall size and footprint of the extruder system 60.

[0076] Figure 7 shows the barrel body 48 and the nozzle 50 of the barrel 10 in more detail. The nozzle 50 comprises a flange 64 (best shown in Figure 8a) proximate to its inlet orifice 66. The flange 64 defines a lip that projects away from an outlet orifice 68 of the nozzle 50. The lip is configured to abut the extruding end of the barrel body 48.

[0077] The extruding end of the barrel body 48 further comprises a threaded exterior surface. A fastening member 52 is configured to secure the nozzle 50 to the extruding end of the barrel body 48 by abutting the nozzle flange 64 and screwing onto the threaded exterior surface of the barrel body 48. The fastening member 52 is preferably a tightening nut such as a hexagonal nut.

[0078] The extruder system 2 additionally comprises one or more replacement nozzles that are releasably couplable to the barrel body 48. The nozzle 50 and the or each replacement nozzle(s) are shaped and / or sized differently to respectively set different extrusion flow rates of the extruder system 2.

[0079] Examples of different nozzles 70, 71 are shown in Figures 8c, 8d and 8e. The nozzle 50 and the or each replacement nozzle(s) have different internal nozzle angles. The internal nozzle angle is defined between an inlet orifice 66 and an outlet orifice 68 of the nozzle, more specifically defined by the angle of the nozzle wall between the inlet orifice 66 and the outlet orifice 68. The internal nozzle angles may range between 30°, as shown in Figure 8b, and 60°, as shown in Figure 8c. Nozzles having a larger internal nozzle angle such as 60° are suited for use with materials that require a low flow rate through the extrusion screw (flow rate per screw turn), while nozzles having a smaller internal nozzle angle such as 45° or less are suited for use with materials that require a high flow rate through the extrusion screw (flow rate per screw turn). The internal nozzle angles may range beyond 90°, or even up to 180° as shown in Figures 8d and 8e. The nozzle 71 having an internal nozzle angle of beyond 90° and / or up to 180° is advantageous for decreasing the flow of low viscosity thermoplastics.

[0080] In a preferred embodiment of the invention, the extruder system may comprise the nozzle and one or more replacement nozzle(s) having different internal nozzle angles for each one of the barrel 10 and the plurality of replacement barrels.

[0081] The size of the nozzle's outlet orifice 48 may be, but is not limited to, 0.2 mm or larger.

[0082] Configuring the nozzle in this manner not only makes it easier to change nozzles but also makes it easier to clean and remove previously used material from the nozzle 50 and extrusion screw 18. Since the fastening member 52 is located outside the barrel 10 and nozzle 50, the molten material does not reach the fastening member 52, which means that the fastening member 62 does not require cleaning. This is particularly advantageous due to fine threads of the barrel body 48 and fastening member 52 not requiring regular cleaning, which not only is tedious and difficult but also would decrease the life span of the part. Additionally such a nozzle 50 is leak-proof and cheaper to produce. Figure 9a-9b show an extruder system 102 according to another embodiment of the invention. The extruder system 102 is similar in structure and operation to the extruder system 2. Like features share the same reference numerals. The extruder system 102 differs from the extruder system 2 in that the extruder system 102 has a wider barrel 10, a larger diameter extrusion screw 18 and an integral nozzle 50.

[0083] Figure 10 shows a 3D printer system 72 comprising an extruder system 2. The 3D printer system additionally comprises a heated chamber 74 for printing objects with high performance materials, such as PEEK & PEI, requiring high temperature conditions. The heated chamber 74 may be configured to reach a temperature of up to 200°C.

[0084] The 3D printer system 72 also comprises a multi-axis motion system. Preferably the multi-axis motion system is a 5-axis motion system 76 in which the feeding and cooling block 4 is configured to move in the X and Y axes and the 3D printer build platform 78 is configured to move in the Z axis, the A axis (rotation about the X axis) and the C axis (rotation about the Z axis). The motion system may use larger stepper motors to account for greater loads in action, such as the increased weight and moments caused by a feeding and cooling block carrying an extrusion screw and pellets. Many components (such as belts, motors, polymeric couplings, gears and electronic components) are configured to be located outside of the heated chamber 74 to increase their longevity.

[0085] The 3D printer system also comprises a build platform 78 such as the one shown in Figure 11. The build platform 78 comprises an upper plate 80 and a lower plate 82 releasably couplable to each other, the upper plate comprising a plurality of holes 84 configured to be filled by melted fusible material to provide anchoring points for 3D printed objects. The two plate setup allows easier subsequent removal of the extruded material used to fill up the holes 84, as removal of the lower plate 82 will allow the extrudate to fall out of the holes 84 or be easily accessed by a removal tool.

[0086] The plurality of holes 84 are arranged to form an array and they are sized as a function of the size of the nozzle orifice opening. The distance between the holes 84 is preferably not larger than 20 mm, more preferably about 10 mm. If the size of a hole 84 is too small, the extrudate will cool down too quickly as it contacts the sidewalls of the hole 84, which causes the material to solidify and thereby impede further filling of the hole 84. This results in a weak anchoring point. For example, for a 0.4 mm diameter nozzle, the hole 84 should be at least 1 mm wide. The build platform 78 can be used with hot or cold material, with any material, and with a single material or multiple materials at once.

[0087] Preferably the build platform 78 is manufactured from the same material or from materials with similar thermal expansion coefficients. This is because thermal expansion of the build platform 78 caused by the heated chamber 74 may otherwise cause warpage of the build platform. Preferably any metal used for the build platform 78 should be made from cast material rather than extruded material, e.g. cast aluminium instead of extruded aluminium, because extruded material is more likely to warp when heated.

[0088] In embodiments of the invention, the 3D printer system may additionally comprise a tool changing system configured to change the extruder system for at least one other tool. This is to aid the 3D printer system 72 in printing using different materials and using other tools. Preferably the tool changing system may be configured to change between multiple tools including any one of a pellet extruder, a filament extruder, a machining tool and a probe. The changing of tools may happen during or outside the 3D printing process. For example, the changing of tools may be designated to automatically take place in a slicing step prior to the start of a 3D printing process. The tool changing system may be capable of automatic tool changing and / or user- demanded tool changing.

[0089] The tool changing system uses a particular kinematic coupling having an elongated triangular pattern 86 and a configuration that makes use of the weight of the extruder system 2. In particular, a pull pin is set in a triangular centre 88 of the triangular pattern 86, as shown in Figure 12, and the weight of the extruder system 2 acts as the load required to weigh down the system.

[0090] Therefore, the kinematic coupling may be used to ensure adequate precision between each tool change, including when the barrel 10, the extrusion screw 18 and / or the nozzle 50 is changed. This is important due to the weight and volume of the extrusion system's components and the fusible material. This is also important due to the complexity of motion of the 3D printer system 72 arising from the use of a multi-axis motion system.

[0091] In addition, the motion system is preferably configured to lift the feeding and cooling block 4 in the Z axis so that the tool changing system can be kept outside of the heated chamber 74. As the 3D printer system 72 is intended to work in a heated chamber 74, the tool changing system is kept out of the heated chamber 74 for tool life improvement. For each tool change, the tool is raised in the Z axis out of the heated chamber 74. This axis is preferably used only during tool changes, and preferably used to set the offset for each tool related to the origin of the motion system. After the existing tool is released and removed, a new tool is installed before being lowered back into the chamber 74. Preferably the tool changing system has larger motors to account for the weight of the tools.

[0092] It will be appreciated that the above numerical values are merely intended to help illustrate the working of the invention and are not necessarily limiting on the scope of the invention.

[0093] The listing or discussion of an apparently prior-published document or apparently prior- published information in this specification should not necessarily be taken as an acknowledgement that the document or information is part of the state of the art or is common general knowledge.

[0094] Preferences and options for a given aspect, feature or parameter of the invention should, unless the context indicates otherwise, be regarded as having been disclosed in combination with any and all preferences and options for all other aspects, features and parameters of the invention.

Claims

CLAIMS1. An extruder system for a fused granulate fabrication 3D printer system, the extruder system comprising: a feeding element configured to receive fusible material; a barrel coupled to the feeding element, the barrel including a nozzle; and an extrusion screw coupled to the feeding element, the extrusion screw being housed inside the barrel and being operable to, in use, drive the fusible material from the feeding element to the nozzle, wherein at least one of the barrel and the extrusion screw is configured to be releasably coupled to the feeding element.

2. An extruder system according to Claim 1 further including at least one replacement extrusion screw, wherein the or each replacement extrusion screw is releasably couplable to the feeding element.

3. An extruder system according to Claim 2, wherein the extrusion screw and the or each replacement extrusion screw are shaped and / or sized differently to respectively set different extrusion flow rates of the extruder system.

4. An extruder system according to Claim 2 or Claim 3, wherein the extrusion screw and the or each replacement extrusion screw have different length to diameter (L / D) ratios.

5. An extruder system according to Claim 4 wherein the length to diameter (L / D) ratios are equal to or smaller than 6: 1.

6. An extruder system according to Claim 4 or Claim 5, wherein the length to diameter (L / D) ratios are equal to or greater than 4.25: 1.

7. An extruder system according to Claim 4 wherein the length to diameter (L / D) ratios are greater than 6: 1.

8. An extruder system according to Claim 4 wherein the length to diameter (L / D) ratios are smaller than 4.25: 1.

9. An extruder system according to any one of Claims 2 to 8, wherein the extrusion screw and the or each replacement extrusion screw have different diameters.

10. An extruder system according to any one of the preceding claims, wherein the feeding element comprises a screw drive coupler, and wherein the extrusion screw is releasably connectable to the screw drive coupler via a quick-release attachment element.

11. An extruder system according to any one of the preceding claims further including at least one replacement barrel, the or each replacement barrel including a nozzle, wherein the or each replacement barrel is releasably couplable to the feeding element.

12. An extruder system according to Claim 11, wherein the barrel and the or each replacement barrel are shaped and / or sized differently to respectively set different extrusion flow rates of the extruder system.

13. An extruder system according to Claim 11 or Claim 12 when dependent on any one of Claims 2 to 9, wherein the barrel and the or each replacement barrel are shaped and / or sized to respectively house the corresponding extrusion screw and the or each corresponding replacement extrusion screw.

14. An extruder system according to any one of the preceding claims, wherein the barrel and / or the extrusion screw is releasably coupled to the feeding element via a fastening member.

15. An extruder system according to any one of the preceding claims, wherein the extruder system comprises a heating element arranged around the barrel, the heating element operable to heat up the barrel.

16. An extruder system according to any one of the preceding claims, wherein the barrel comprises at least two barrel parts, the at least two barrel parts being releasably couplable to each other.

17. An extruder system according to any one of the preceding claims, wherein the barrel includes a barrel body, wherein the nozzle is releasably coupled to the barrel body, wherein the extruder system further includes at least one replacement nozzle, wherein the or each replacement nozzle is releasably couplable to the barrel body, wherein the nozzle and the or each replacement nozzle are shaped and / or sized differently to respectively set different extrusion flow rates of the extruder system.

18. An extruder system according to Claim 17, wherein the nozzle and the or each replacement nozzle have different internal nozzle angles, the internal nozzle angles ranging between 30° and 180°.

19. An extruder system according to Claim 17 or Claim 18 when dependent on any one of Claims 11 to 13, wherein the nozzle and the or each replacement nozzle are shaped and / or sized to be respectively releasably couplable to the barrel body of the corresponding barrel and the or each corresponding replacement barrel.

20. An extruder system according to Claim 19, wherein the nozzle and the or each replacement nozzle are respectively releasably couplable to the barrel body of the corresponding barrel and the or each replacement barrel via a fastening member.

21. An extruder system according to any one of Claims 17 to 20, wherein the nozzle comprises a flange defining a lip that projects away from an outlet orifice of the nozzle, the lip being configured to contact an extruding end of the barrel body.

22. An extruder system according to any one of the preceding claims, wherein the feeding element is pivotable in a vertical plane to change an axial orientation of the barrel and extrusion screw relative to a horizontal plane.

23. An extruder system according to any one of the preceding claims wherein the feeding element is additionally configured as a fluid-cooled cooling element.

24. An extruder system for a fused granulate fabrication 3D printer system, the extruder system comprising: a feeding element configured to receive fusible material; a barrel coupled to the feeding element, the barrel including a barrel body and a nozzle, wherein the nozzle is releasably coupled to the barrel body; and an extrusion screw coupled to the feeding element, the extrusion screw being housed inside the barrel and being operable to, in use, drive the fusible material from the feeding element to the nozzle, wherein the extruder system further includes at least one replacement nozzle, wherein the or each replacement nozzle is releasably couplable to the barrel body, wherein the nozzle and the or each replacement nozzle are shaped and / or sized differently to respectively set different extrusion flow rates of the extruder system.

25. An extruder system according to Claim 24, wherein the nozzle and the or each replacement nozzle have different internal nozzle angles, the internal nozzle angles ranging between 30° and 180°.

26. An extruder system according to Claim 25, wherein the nozzle comprises a flange defining a lip that projects away from an outlet orifice of the nozzle, the lip being configured to contact an extruding end of the barrel body.

27. A 3D printer system comprising the extruder system according to any one of the preceding claims.

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