Liquefier for additive manufacturing system based on extrusion process and method of manufacturing thereof

Abstract

A liquefier tube (5) for an extrusion head (4) for use in an additive manufacturing system (1) based on an extrusion process. The liquefier (5) forms a passage (P) having an inlet portion (57) and an outlet (55) downstream of the inlet portion (57). The inlet portion (57) has a substantially circular cross-section for receiving filament material. The passage (P) transitions from the inlet portion (57) to a non-circular portion (53) downstream of the inlet portion (57) and having a non-circular cross-section.

Description

[0001] The present invention relates generally to a liquefier for use in an extrusion process based additive manufacturing (EAM) system. More particularly, but not exclusively, the present invention relates to a liquefier tube, a liquefier assembly, an extrusion head, and a method of manufacturing a liquefier tube for use in an EAM system.

[0002] Extrusion process based additive manufacturing systems, such as fused filament fabrication (FFF) systems, are used to build physical objects via a digital representation in a layer-by-layer manner by extruding a molten feed material through a nozzle.

[0003] The feed material is typically in the form of a continuous filament of thermoplastic material. Typically, the filament is fed from a spool and advanced through a moveable extrusion head comprising a liquefier assembly. The liquefier assembly is configured to melt the filament so that it can be extruded through a nozzle and deposited on a print bed.

[0004] The liquefier assembly comprises a liquefier section, which can be in the form of a tube, along which the filament is advanced, and a heater or heater cartridge located externally of the liquefier tube. The heater heats the liquefier section and, as a result of heat transfer, the filament. The temperature of the filament is raised above its melting point so that it liquefies and allows material to be extruded from the nozzle. Extrusion pressure is applied as a result of the continued advancement of the filament upstream of the nozzle.

[0005] Conventionally, the filament and the duct or channel in or along the liquefier section has a substantially circular cross-section. It has been observed that, due to the low thermal conductivity of thermoplastic materials, heat from the heater does not efficiently and quickly transfer to the centre of the circular filament. This in turn can have a negative impact on both the rate and quality of the extrusion process.

[0006] It is therefore a first, non-exclusive, object of the present invention to provide a liquefier which overcomes or at least alleviates the drawbacks of the prior art.

[0007] It is a further non-exclusive object of the present invention to provide an improved liquefier, liquefier tube, liquefier assembly, extrusion head and method of manufacturing a liquefier.

[0008] It is therefore a first aspect of the present invention to provide a method of manufacturing a liquefier or liquefier tube, for example for use in an extrusion process based additive manufacturing system, the method comprising: providing a tubular body having a substantially circular cross-section; deforming or extruding the tubular body at a location spaced apart from one of the two ends of the tubular body so as to provide an inlet portion having a substantially circular cross-section for receiving a filament material and a non-circular portion downstream of the inlet, the non-circular portion having a non-circular cross-section.

[0009] The method can include providing the tubular body with a substantially constant wall thickness.

[0010] The method can include providing (e.g., forming, attaching, or connecting) an extrusion tip at the other end of the two ends of the tubular body, e.g., opposite the inlet portion, to form an outlet for dispensing the material in a molten state. Providing the extrusion tip can include forming, attaching, or connecting the extrusion tip to the other end of the tubular body, e.g., opposite the inlet portion. The extrusion tip can form or have, e.g., the outlet for dispensing the material in a molten state.

[0011] The method can include deforming or extruding the tubular body at a location spaced apart from one end of the two segments of the tubular body, e.g., opposite the inlet portion, such that the tubular body transitions from the substantially circular inlet portion to a non-circular portion downstream of the inlet.

[0012] The method can include deforming the tubular body by hydroforming. Deforming the tubular body by hydroforming can include placing the tubular body or a portion thereof in a forming tool or between a pair of dies. Deforming the tubular body by hydroforming can include injecting a liquid under pressure into a passageway formed by the tubular body to deform the tubular body or a portion thereof, e.g., such that the tubular body conforms to a profile defined by the forming tool or the pair of dies.

[0013] According to another aspect of the present invention, there is provided a method of manufacturing a liquefier or liquefier tube, e.g., for use in an extrusion process-based additive manufacturing system, the method comprising: deforming a material of a first sheet to form a first portion of the liquefier or liquefier tube; deforming a material of a second sheet to form a second portion of the liquefier or liquefier tube; and attaching the first portion to the second portion to form a tubular body of the liquefier or liquefier tube.

[0014] The method can include deforming the first sheet and / or the second sheet into a pipe segment. The method can include deforming the first sheet and / or the second sheet using a press, a former, or a metal punch. The method can include deforming the first sheet and / or the second sheet by hydroforming. The method can include deforming the first sheet and / or the second sheet by stamping or forming.

[0015] The first sheet and / or the second sheet can be or include a metal, e.g., stainless steel. The first sheet and / or the second sheet can be or include brass, copper, tungsten, titanium, molybdenum, beryllium copper, or any suitable other metal or alloy.

[0016] The first sheet and / or the second sheet can include a polymeric material. The method can include heating the first sheet and / or the second sheet prior to deforming, e.g., above its glass transition temperature and / or to increase ductility and / or malleability.

[0017] The first part and / or the second part of the liquefier or liquefier tube can comprise one half of the liquefier, the liquefier tube or the tubular body of the liquefier tube, respectively.

[0018] The first part can be attached to the second part by welding or brazing.

[0019] According to another aspect of the present application, there is provided a method of manufacturing a liquefier or liquefier tube, for example for use in an additive manufacturing system based on an extrusion process, the method comprising: providing a first piece of material to machine a first part of a liquefier or a first part of a liquefier tube in a surface of the first piece; providing a second piece of material to machine a second part of the liquefier or a second part of the liquefier tube in a surface of the second piece; and joining the first piece and the second piece together to form a passageway of the liquefier or a passageway of the liquefier tube.

[0020] The first piece and / or the second piece can comprise a metal, for example stainless steel. The first piece and / or the second piece can be formed from or comprise brass, copper, tungsten, titanium, molybdenum, beryllium copper or any other suitable metal or alloy.

[0021] The first piece and the second piece can be connectable to each other, for example removably connectable to each other, so as to form the liquefier, the liquefier tube or a passageway thereof.

[0022] According to an aspect of the present application, there is provided a liquefier, for example for use in an additive manufacturing system based on an extrusion process, the liquefier forming a passageway having an inlet portion, for example for receiving a filament material, and an outlet downstream of the inlet, wherein the passageway transitions from the inlet portion to a non-circular portion downstream of the inlet, the non-circular portion having a non-circular cross-section.

[0023] The liquefier can comprise a tube or a hollow or tubular body, the liquefier can have a substantially circular cross-section. The outlet can comprise an extrusion tip, for example for dispensing material in a molten state.

[0024] According to another aspect of the present application, there is provided a liquefier tube, for example for use in an additive manufacturing system based on an extrusion process, the liquefier tube comprising: a tubular body; an inlet portion having a substantially circular cross-section, for example for receiving a filament material; an outlet downstream of the inlet; and an extrusion tip for dispensing material in a molten state, wherein the tubular body transitions from the substantially circular inlet portion to a non-circular portion downstream of the inlet, the non-circular portion having a non-circular cross-section.

[0025] The liquefier or body can have a substantially constant wall thickness.

[0026] Advantageously, providing a tubular body having a substantially constant wall thickness allows the liquefier tube to be manufactured more easily and more cheaply.

[0027] The extrusion tip can be formed from or include a nozzle. The method can include providing (e.g. forming, attaching or connecting) a nozzle, for example at the other end of the body.

[0028] The extrusion tip or nozzle can be removably connected to the liquefier or body, for example. The extrusion tip or nozzle can be brazed or welded to the liquefier or body.

[0029] The method can include forming, attaching or connecting the extrusion tip or nozzle to the liquefier, liquefier tube or body, for example removably. The method can include brazing or welding the extrusion tip or nozzle to the liquefier, liquefier tube or body, for example the other end of the body.

[0030] The non-circular portion of the liquefier or body can include a deformed portion or an extruded portion.

[0031] In these examples, deforming or extruding the liquefier or body, or providing a non-circular portion includes deforming or extruding the liquefier or body in a first region, for example to provide a first section or first segment, and deforming or extruding the liquefier or body in a second region, for example to provide a second section or second segment. The non-circular portion can include the first section or first segment and / or the second section or second segment.

[0032] The liquefier or body can be deformed, for example by extruding a first region to provide a first section of the non-circular portion. The liquefier or body can be deformed, for example by extruding a second region downstream of the first region to provide a second section of the non-circular portion downstream of the first section. The first section and / or the second section can be non-circular.

[0033] In these examples, deforming or extruding the liquefier or body includes pressing the liquefier or body. Deforming or extruding the liquefier or body can include pressing the liquefier or body in a first region, for example to provide a first section or first segment, and pressing the liquefier or body in a second region, for example to provide a second section or second segment.

[0034] In these embodiments, the method can include pressing, deforming or extruding the liquefier or body to a first extent in a first region and / or pressing, deforming or extruding the liquefier or body to a second extent, for example greater than the first extent, in a second region, for example to provide a tapered profile.

[0035] The second region or second section or second segment can be downstream of the first region or first section or first segment.

[0036] The non-circular portion of the liquefier or body can extend along a portion of the length, e.g., along a longitudinal axis or major axis of the liquefier, liquefier tube, or body.

[0037] The non-circular portion of the liquefier or body can include a tapered cross-sectional profile. The flow area of the passageway of the non-circular portion of the liquefier or body can include a tapered profile. The non-circular portion can taper along a portion of the length of the liquefier or body, e.g., along a longitudinal axis or major axis of the liquefier or body. The non-circular portion can have a major dimension and a minor dimension. The minor dimension can taper, e.g., along a portion of the length of the non-circular portion. The minor dimension can decrease, e.g., along a portion of the length of the non-circular portion.

[0038] According to embodiments of the present invention, it is advantageous to provide tapering because as the filament advances along the liquefier or liquefier tube, the molten portion (located near the wall of the tubular body) moves toward the center of the flow path or passageway. In addition, the distance that heat must travel to reach the center of the passageway or flow path is reduced.

[0039] The non-circular portion of the liquefier or body can include a plurality of segments or sections. Each segment or section of the plurality of segments or sections can include a deformed or extruded segment of the liquefier or body. Each segment or section of the plurality of segments or sections can be arranged, e.g., continuously, along a length or major axis of the liquefier, liquefier tube, or body. Each segment or section of the plurality of segments or sections can be arranged along a longitudinal axis of the liquefier, liquefier tube, or body.

[0040] Each segment or section of the plurality of segments or sections (hereinafter referred to as a segment) can have, e.g., a different cross-sectional shape, configuration, or cross-sectional profile from one another. One segment of the plurality of segments (e.g., a first segment) can have a different cross-sectional shape, configuration, or cross-sectional profile from another segment of the plurality of segments (e.g., a second segment). The flow area of the passageway of one segment of the plurality of segments (e.g., a first segment) or the flow area of the passageway in one segment of the plurality of segments (e.g., a first segment) can have, e.g., a different cross-sectional shape, configuration, or cross-sectional profile from the passageway of another segment of the plurality of segments (e.g., a second segment) or the passageway in another segment of the plurality of segments (e.g., a second segment).

[0041] The minor axis dimension of the first of the segments can be greater than the minor axis dimension of the second of the segments, e.g., the respective minor axis dimensions. The major axis dimension of the first of the segments can be less than the major axis dimension of the second of the segments, e.g., the respective major axis dimensions. The second segment can be downstream of the first segment.

[0042] The first segment can be deformed so as to have a minor axis dimension that is greater than the minor axis dimension of the deformed second segment.

[0043] The method can include pressing the liquefier or body to a first extent or first size in a first region to provide the first segment. The method can include pressing the liquefier or body to a second extent or second size in a second region to provide the second segment. The second extent or second size can be different than, e.g., greater than or less than, the first extent or first size.

[0044] In some examples, the first and second segments, e.g., their major axis dimensions and / or minor axis dimensions, are rotationally offset or skewed from one another. The first and second segments can be skewed or rotated to or with respect to one another. The first and second segments can include a skew angle formed therebetween. The first segment can include a portion of the liquefier or body that is deformed or extruded in a direction that is skewed or rotationally offset with respect to a direction of deformation or extrusion of the second segment.

[0045] Corresponding minor axis dimensions and / or major axis dimensions of the first and second segments can be rotationally offset or skewed from one another.

[0046] The liquefier or body can be deformed such that the minor axis dimension and / or major axis dimension of the first segment and the corresponding minor axis dimension and / or major axis dimension of the second segment are rotationally offset from one another.

[0047] Providing the rotational offset or skew facilitates improving heat transfer characteristics of the liquefier, liquefier tube, or body by creating a tortuous flow path for the molten material. Such a flow path promotes mixing of the molten or melted material as it progresses along the liquefier, liquefier tube, or body, thereby allowing for more uniform heat distribution through the material.

[0048] The method can include pressing, deforming, or extruding the liquefier or body in a first direction in a first region and pressing, deforming, or extruding the liquefier or body in a second direction in a second region, the second direction being skewed or rotationally offset with respect to the first direction.

[0049] The cross-section (e.g., cross-sectional shape) of the first segment (or passageway thereof or therein) and / or the second segment (or passageway thereof or therein) can include an axis of symmetry. The axis of symmetry of the first segment (e.g., cross-sectional shape of the first segment) and the corresponding axis of symmetry of the second segment (e.g., cross-sectional shape of the second segment) can be rotationally offset or skewed from one another.

[0050] In these embodiments, the liquefier or body includes a substantially circular portion between the two or more segments. The liquefier or body can include a substantially circular portion between the first segment and the second segment.

[0051] The liquefier or body is deformable to include a substantially circular portion intermediate the first segment and the second segment.

[0052] The non-circular portion (or passageway thereof or therein) or the non-circular cross-section of the liquefier or body is deformable such that one or more segments thereof can be substantially stadium-shaped, disc-rectangular, or oblong.

[0053] The non-circular portion or the non-circular cross-section of one or more segments thereof (or passageway thereof or therein) can be ovate, elliptical, regular polygonal, irregular polygonal, simple convex polygonal, or simple concave polygonal.

[0054] The non-circular portion or the non-circular cross-section of one or more segments thereof (or passageway thereof or therein) can be star-shaped.

[0055] The transition or change from the substantially circular portion to the non-circular portion or one or more segments thereof can include a continuous transition, a gradual transition, and / or a tapered transition.

[0056] The transition or change from the substantially circular portion to the non-circular portion or one or more segments thereof can include a segmented transition, a discrete transition, and / or a stepped transition.

[0057] The liquefier or liquefier tube can include a substantially circular portion downstream of the non-circular portion, or segment of the portion.

[0058] The first segment (or passageway thereof or therein) can have a different cross-sectional shape, configuration, or cross-sectional profile than the second segment (or passageway thereof or therein).

[0059] In these examples, the non-circular portion can include a first non-circular portion and a second non-circular portion. The first non-circular portion and / or the second non-circular portion can include a plurality of segments or sections. Each segment or section of the plurality of segments or sections can include a deformed or extruded segment of the liquefier or body.

[0060] Each of the plurality of segments or sections can be arranged, e.g., continuously, along a length or major axis of the liquefier, liquefier tube, or body and / or the first non-circular portion and / or the second non-circular portion. Each of the plurality of segments or sections can be arranged along a longitudinal axis of the liquefier, liquefier tube, or body.

[0061] The first non-circular portion and / or the second non-circular portion, e.g., their major axis dimensions and / or minor axis dimensions, can be rotationally deflected, curved, or skewed relative to one another. Respective segments or sections of the first non-circular portion and / or the second non-circular portion, e.g., their major axis dimensions and / or minor axis dimensions, can be rotationally deflected or skewed relative to one another.

[0062] The first non-circular portion and the second non-circular portion can include a skew angle formed therebetween. The skew angle can include 90°, 60°, 45°, 30°, or other angles. The first non-circular portion or a plurality of segments or sections thereof can include a portion of the body that is deformed or extruded in a direction that is skewed or rotationally deflected relative to a direction of deformation or extrusion of the second non-circular portion or a plurality of segments or sections thereof.

[0063] Respective minor axis dimensions and / or major axis dimensions of the first non-circular portion and the second non-circular portion can be rotationally deflected or skewed relative to one another. The liquefier or body can be deformed such that the minor axis dimension and / or the major axis dimension of the first non-circular portion and the respective minor axis dimension and / or the major axis dimension of the second non-circular portion are rotationally deflected relative to one another.

[0064] The first non-circular portion and the second non-circular portion can include a transition region or zone therebetween. The transition region or zone can extend along a portion of a length of the liquefier, liquefier tube, or body. The transition region or zone can include or accommodate a skew of the first non-circular portion and the second non-circular portion or one or more segments thereof relative to one another.

[0065] The method can include deforming, extruding, or pressing the liquefier or body in the first region to form a first segment (or a passage thereof or therein) having a first cross-sectional shape. The method can include deforming, extruding, or pressing the liquefier or body in the second region to form a second segment (or a passage thereof or therein) having a second cross-sectional shape, e.g., different from the first cross-sectional shape.

[0066] Deforming, extruding or pressing the liquefier or body can comprise placing the liquefier or body in a press. Deforming, extruding or pressing the liquefier or body can comprise placing the liquefier or body in a forming machine, for example between a punch and a die or between a pair of dies. The liquefier or body can be deformed, extruded or pressed by rollers, for example a pair of opposing rollers, for example to form a continuous transition between the inlet portion and the non-circular portion. The press can comprise one or more rollers, for example opposing rollers. Deforming, extruding or pressing the liquefier or body can comprise deforming, extruding or pressing the liquefier or body in segments, for example discrete segments.

[0067] The internal diameter of the liquefier, body or inlet portion thereof can be between 1 mm and 4 mm, for example between 1.5 mm and 3.5 mm, for example between 1.75 mm and 3.25 mm. The diameter of the liquefier or body can be 2.0 mm or 3.0 mm.

[0068] The liquefier or body can comprise a thin-walled tube. The liquefier or body or thin-walled tube can comprise or be made of a thermally conductive material.

[0069] The wall thickness of the liquefier or body can be less than 1 mm, preferably less than 0.75 mm, for example between 0.1 mm and 0.5 mm.

[0070] The length of the liquefier tube or body can be 100 mm or less (for example 90 mm or less) or 80 mm or less (for example 70 mm or less). The length of the liquefier or body can be between 10 mm and 100 mm, for example between 10 mm and 70 mm, for example between 15 mm and 60 mm.

[0071] The liquefier, liquefier tube or body can comprise a heating zone. The heating zone can be configured to be heated in use. The heating zone and the non-circular portion can coincide or overlap. The heating zone can surround or encircle the non-circular portion.

[0072] The heating zone can be a portion or length of the liquefier or body to which heat is applied or to which heat is applied, for example to melt filament material that is being advanced along the heating zone. The length of the heating zone can be less than 100 mm, for example less than 90 mm, less than 80 mm, less than 70 mm or less than 60 mm. The length of the heating zone can be 56 mm, 26 mm or 16 mm.

[0073] The inner diameter of the extrusion tip or nozzle can be less than the inner diameter of the liquefier or body. The extrusion tip or nozzle can have a size of 3 mm or less, for example 2.5 mm or less. The extrusion tip or nozzle can have a size between 0.05 mm and 2.5 mm, for example between 0.1 mm and 1.5 mm or between 0.1 mm and 1.4 mm.

[0074] The liquefier or liquefier tube can comprise a substantially circular portion at or towards the outlet. The extrusion tip or nozzle (or a passage thereof or therein) can comprise a substantially circular portion or a substantially circular cross-section.

[0075] The non-circular portion or a segment or segments thereof can be located between the inlet and the outlet. The non-circular portion or a segment thereof can flare or open towards the outlet.

[0076] In these embodiments, the substantially circular portion (or a passage thereof or therein) and the non-circular portion (or a segment or segments thereof) can have substantially equal cross-sectional areas. The non-circular portion or a segment or segments thereof (or a passage thereof or therein) can have a substantially constant cross-sectional area. The passage of the non-circular portion (or a segment or segments thereof) or a passage in the non-circular portion (or a segment or segments thereof) can have a substantially constant flow area.

[0077] The liquefier or body can be deformed such that the substantially circular portion (or a passage thereof or therein) and the non-circular portion (or a passage thereof or therein) have substantially equal cross-sectional areas. The liquefier or body can be deformed such that the passage of the substantially circular portion (or a passage in the substantially circular portion) and the non-circular portion have substantially equal flow areas.

[0078] The liquefier or body and / or a passage can have or comprise a constant or substantially constant hydraulic diameter. The non-circular portion, the first non-circular portion and / or the second non-circular portion can have or comprise a constant or substantially constant hydraulic diameter.

[0079] The hydraulic diameter is defined by the equation:

[0080] D H = 4A / P

[0081] where D H is the hydraulic diameter, A is the flow area, and P is the perimeter defined by the tubular body.

[0082] Providing a liquefier or liquefier tube having a constant or substantially constant hydraulic diameter provides a substantially constant pressure as the filament material progresses along it in use.

[0083] Thus, in the case of a liquefier or liquefier tube, the change in cross-sectional shape in the non-circular portion, the first non-circular portion and / or the second non-circular portion allows heat to be transferred more efficiently to the filament material as it advances, but at the same time does not increase the pressure that needs to be applied to produce a given flow rate.

[0084] The liquefier or body can be made of or formed from or comprise a metal. The liquefier or body can be made of or comprise stainless steel. In these embodiments, the liquefier or body can be made of or comprise brass, copper, tungsten, titanium, molybdenum, beryllium copper or any other suitable metal or alloy.

[0085] The liquefier or body can be made of or comprise a polymeric material, for example a thermally conductive polymeric material. The melting point and / or glass transition temperature of such a polymeric material is preferably substantially higher than the filament material to be melted.

[0086] The liquefier, liquefier tube or body can comprise a heating zone. The heating zone can be configured to be heated in use. The heating zone and the non-circular portion can coincide or overlap. The heating zone can surround or encircle the non-circular portion.

[0087] According to another aspect of the present application, there is provided a liquefier assembly for use in an additive manufacturing system based on an extrusion process, the liquefier assembly comprising a liquefier or liquefier tube as described above, and a heating means, for example a heater, heating element, heater element or heater cartridge, for heating filament material advancing in use into or along the liquefier or liquefier tube.

[0088] The heating means can comprise a heating block or heater block. The heating block or heater block can comprise a heating element or heating cartridge. The heating means can at least partially surround the liquefier or liquefier tube and / or can surround or be located in the vicinity of a heating zone of the liquefier or liquefier tube. The heating element or heating cartridge can extend along the length of the heating block or heater block.

[0089] The heating means, for example a heater, heating block or heater block, can be clamped around the liquefier or liquefier tube. The heating means, heating block or heater block can comprise a temperature sensor. The heating cartridge or heating element and / or the temperature sensor can be operatively connected to a controller, respectively, for example to provide closed loop temperature control.

[0090] According to another aspect of the present application, there is provided an extrusion head or extruder comprising a liquefier or liquefier tube as described above, or a liquefier assembly as described above.

[0091] The extrusion head or extruder can comprise a feeder or feeding mechanism. The feeder or feeding mechanism can be located upstream of the liquefier, liquefier tube or liquefier assembly. The feeder or feeding mechanism can be configured, in use, to advance filament material into and / or along the liquefier or liquefier tube.

[0092] The feeder or feeding mechanism can comprise one or more rotatable members or gears which can be configured, in use, to contact the surface of the filament being fed or advanced into the liquefier, liquefier tube or liquefier assembly.

[0093] The feeder or feeding mechanism can comprise a pair of, for example, opposing, rotatable members or gears which can be configured, in use, to contact the surface of the filament being fed or advanced into the liquefier, liquefier tube or liquefier assembly.

[0094] The feeder or feeding mechanism or one or more rotatable members can comprise a feed roller. The feeder or feeding mechanism or one or more rotatable members can comprise a pair of feed rollers.

[0095] At least one or each feed roller can be driven, for example, by a stepper motor.

[0096] One or more of the rotatable members can comprise one or more surface features which can be configured, in use, to engage with or pinch the surface of the filament material received in or being fed or advanced into the liquefier, liquefier tube or liquefier assembly.

[0097] The surface features can comprise one or more shaped features. The surface features can comprise one or more grooves, protrusions or ribs.

[0098] According to another aspect of the application there is provided an additive manufacturing system comprising a liquefier or liquefier tube as described above, a liquefier assembly as described above or an extrusion head as described above.

[0099] The additive manufacturing system can be a fused filament fabrication (FFF) system.

[0100] For the avoidance of doubt, any feature described herein is equally applicable to any aspect of the application. For example, a liquefier or liquefier tube can comprise any one or more features of a liquefier assembly, extrusion head or additive manufacturing system associated with the liquefier or liquefier tube and vice versa. Similarly, the method can comprise any one or more features or steps associated with one or more features of a liquefier, liquefier tube, liquefier assembly, extrusion head or additive manufacturing system.

[0101] Another aspect of the present application provides a computer program element comprising and / or forming and / or defining a three-dimensional design for use with a simulation device or a three-dimensional additive or subtractive manufacturing device or apparatus, such as a three-dimensional printer or a computer numerical control machine tool, the three-dimensional design comprising embodiments of the liquefier, the liquefier tube, the liquefier assembly, the extrusion head and / or the additive manufacturing system as described above.

[0102] Another aspect of the present application provides a computer program element comprising computer readable program code means for causing a processor to perform a procedure to implement one or more steps of the above described method.

[0103] Yet another aspect of the present application provides a computer program element embodied on a computer readable medium.

[0104] Yet another aspect of the present application provides a computer readable medium having stored thereon a program, wherein the program is arranged to cause a computer to perform a procedure to implement one or more steps of the above described method.

[0105] Yet another aspect of the present application provides a control device or control system or controller comprising the above described computer program element or computer readable medium.

[0106] For the purposes of the present disclosure, and notwithstanding the above, it should be understood that any controller, control unit, and / or control module described herein can comprise a control unit or computing device having one or more electronic processors, respectively. The controller can comprise a single control unit or electronic controller, or alternatively, different functions of control of the system or device can be implemented in or hosted by different control units or controllers or control modules. As used herein, the terms "control unit" and "controller" should be understood to include both a single control unit and controller, as well as multiple control units and controllers operating in concert to provide the required control functionality. A set of instructions can be provided that, when executed, cause the controller or control unit or control module to implement the control techniques described herein, including the methods described herein. The set of instructions can be implemented in one or more electronic processors, or alternatively, can be provided as software to be executed by one or more electronic processors. For example, a first controller can be implemented in software running on one or more electronic processors, and one or more other controllers can also be implemented in software running on one or more electronic processors, optionally the same one or more processors as the first controller. It should be understood, however, that other arrangements are useful, and therefore the application is not intended to be limited to any particular device. In any case, the set of instructions can be embedded in a computer-readable storage medium (e.g., a non-transitory storage medium), which can include any mechanism for storing information in a form readable by a machine or electronic processor / computing device, including, but not limited to, magnetic storage media (e.g., floppy disks), optical storage media (e.g., CD-ROMs), magneto-optical storage media, read-only memory (ROM), random-access memory (RAM), erasable programmable memory (e.g., EPROM and EEPROM), flash memory, or the like.

[0107] Within the scope of this application, it is explicitly intended that the various aspects, embodiments, examples, and alternatives set forth in the preceding paragraphs, in the claims, and / or in the following description and drawings, as well as their individual features, may be adopted independently or in any combination. That is, all embodiments and / or features of any embodiment may be combined in any manner and / or combination, unless such features are incompatible. For the avoidance of ambiguity, the terms “may,” “and / or,” “such as,” “e.g.,” and any similar terms as used herein shall be construed as non-limiting, such that the presence of any of the described features is not required. Indeed, any combination of optional features is expressly contemplated without departing from the scope of the invention, whether or not such features are explicitly claimed. The applicant reserves the right to accordingly amend any originally filed claim or to file any new claim, including the right to modify any originally filed claim to subordinate to and / or incorporate any feature of any other claim, even if not originally claimed in this manner.

[0108] Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, in which:

[0109] Figure 1 This is a schematic diagram of an additive manufacturing system incorporating some aspects of the present invention;

[0110] Figure 2 It is a three-dimensional view of the liquefier tube based on the first example;

[0111] Figure 3 yes Figure 2 Side view of the liquefier pipe;

[0112] Figure 4 yes Figure 2 and Figure 3 A cross-sectional view of the liquefier pipe;

[0113] Figure 5 yes Figures 2 to 4 End view of the liquefier tube;

[0114] Figure 6 It is a perspective view of the liquefier tube based on another example;

[0115] Figure 7 yes Figure 6 Side view of the liquefier pipe;

[0116] Figure 8 yes Figure 6 and Figure 7 A top view of the liquefier pipe;

[0117] Figure 9 yes Figures 6 to 8 End view of the liquefier tube;

[0118] Figure 10 is an isometric view of a block liquefier;

[0119] Figure 11 is an isometric view of one half of a block liquefier of Figure 10

[0120] Figure 12 is a cross-sectional view of a block liquefier of Figure 10

[0121] Figure 13 is an isometric view of a liquefier tube according to another example;

[0122] Figure 14 is a side view of a liquefier tube of Figure 13

[0123] Figure 15 is a cutaway isometric view of a liquefier tube of Figure 13 and Figure 14

[0124] Figure 16 is an end view of a liquefier tube of Figures 13 to 15

[0125] Figure 17 is an isometric view of a liquefier tube according to another example;

[0126] Figure 18 is a side view of a liquefier tube of Figure 17

[0127] Figure 19 is a top view of a liquefier tube of Figure 17 and Figure 18

[0128] Figure 20 is a cutaway isometric view of a liquefier tube of Figures 17 to 19

[0129] Figure 21 is an end view of a liquefier tube of Figures 17 to 20

[0130] Reference is now made to Figure 1 which shows a schematic view of an extrusion process based additive manufacturing system 1 comprising a print bed table 2, a gantry 3 located above the print bed table 2, and an extrusion head 4 carried by the gantry 3 and movable along the gantry. The gantry 3 is in the form of a guide rail system configured to allow the extrusion head 4 to move in a horizontal plane within boundaries defined by the print bed table 2. The gantry 3 is supported above the print bed table 2 by a structural frame F.

[0131] ​​​​​​​​​The extrusion head 4 comprises a liquefier assembly, in this example having a liquefier tube 5 (in particular, as shown in Figures 2 to 5

[0132] Reference is now made to Figures 2 to 5 , which illustrate a liquefier tube 5 for use in a manufacturing system 1 for manufacturing a Figure 1 .

[0133] The liquefier tube 5 comprises a tubular body 50 which provides a passageway or flow path (hereinafter referred to as a passageway) P extending along the tubular body, and a wall thickness t of a side wall of the tubular body is constant along a longitudinal axis L (in particular, as shown in Figure 5

[0134] The first, upstream end of the liquefier tube 5 is provided with an inlet portion 51 having a substantially circular cross-section. The second, downstream end 52 of the liquefier tube 5, opposite the inlet portion 51, is also provided with a substantially circular cross-section. The inlet portion 51 and the second end 52 are located at opposite ends of the tubular body 50.

[0135] Intermediate the inlet portion 51 and the second end 52 is a non-circular portion 53 having a non-circular cross-section, in this example in the form of an oblong cross-section. In the present example, the non-circular portion 53 extends uninterruptedly along a portion of the length of the tubular body 50, and has a substantially constant cross-sectional area. A first end portion 57 having a substantially circular cross-section extends between the inlet portion 51 and the non-circular portion 53 along a portion of the length of the tubular body 50.

[0136] In the present example, the non-circular portion 53 has 4 discrete segments: a first segment 53a, a second segment 53b downstream of the first segment 53a, a third segment 53c downstream of the second segment 53b, and a fourth segment 53d downstream of the third segment 53c. Each of the segments 53a to 53d is arranged continuously along the longitudinal axis L of the tubular body 50.

[0137] The tubular body 50 is deformed by extrusion to provide the non-circular portion 53. In the present example, each of the segments 53a to 53d corresponds to an extrusion point / zone at which the tubular body 50 is deformed. A substantially continuous transition is provided between each of the segments 53a to 53d and between the first end portion 57 and the non-circular portion 53.

[0138] ​​The tubular body 50 comprises a continuous transition when viewing the non-circular cross-section of the first section 53a from the substantially circular cross-section of the inlet portion 51 downstream. In this example, the cross-sectional area at the inlet portion 51 is substantially equal to the cross-sectional area of the first section 53a.

[0139] Each of the sections 53a-d has a major axis dimension M1 and a minor axis dimension M2. When viewed downstream of the inlet portion 51 towards the second end 52, the major axis dimension M1 increases and the minor axis dimension M2 decreases, at the fourth section 53d the major axis dimension M1 reaches its maximum value and the minor axis dimension M2 reaches its minimum value.

[0140] Throughout the non-circular portion 53, the minor axis dimension M2 is less than the diameter of the inlet portion 51 and the diameter of the second end 52. Thus, when compared to the substantially circular cross-section of the inlet portion 51 and the substantially circular cross-section of the second end 52, the distance from the side wall of the tubular body 50 to the centre of the passageway P is reduced in the non-circular portion 53.

[0141] Downstream of the fourth section 53d, the non-circular portion 53 transitions from a non-circular cross-section to a second end portion 54 having a substantially circular cross-section at the downstream end 52. The second end portion 54 extends along a portion of the length of the tubular body 50 between the non-circular portion 53 and the downstream end 52.

[0142] The second end 52 is provided with an extrusion tip 55 in the form of a nozzle for dispensing filament material (not shown) in a molten state. The extrusion tip 55 provides an outlet of the liquefier tube 5 and has a substantially circular passageway 56 (specifically, shown in Figure 5 ) extending along the liquefier tube. In this example, the extrusion tip 55 is welded to the tubular body 50 at the second end 52. As Figure 5 is most clearly shown, the circular passageway 56 of the extrusion tip 55 has a smaller cross-sectional area than the passageway of the tubular body 50.

[0143] In use, the liquefier tube 5 is received within an extrusion head 4 of the extrusion process based additive manufacturing system 1 (specifically, as shown in Figure 1 ). Filament material is fed into the inlet portion 51 by a feed mechanism 6. The substantially circular cross-section of the inlet portion 51 is configured to receive, in use, filament material having a circular cross-section from the feed mechanism 6.

[0144] The filament material is advanced along the tubular body 50. A heating means H (specifically, as shown in Figure 1 ) in the form of one or more heating elements in this example, is located within the extrusion head 4 and adjacent to the liquefier tube 5. The one or more heating elements heat the outer surface of the liquefier tube 5 which in turn heats the filament material as it is advanced due to heat transfer.

[0145] As the filament material progresses from the inlet portion 51 towards the non-circular portion 53, the filament material melts due to the heating. The cross-sectional shape of the filament material then conforms to the cross-sectional shape of the non-circular portion 53.

[0146] In the non-circular portion 53, the distance from the heating means H to the centre of the passageway P is reduced, and therefore the distance from the heating means to the centre of the filament material or to the filament flow path is reduced, thereby allowing heat to more effectively reach the centre of the filament material. This allows heat to be more effectively transferred from the heating means H to the filament material.

[0147] The extrusion pressure is generated by the feed of the filament upstream. The molten filament is extruded from the extrusion tip 55 and extruded onto the build plate table 2 (in particular, as shown more clearly in Figure 1 ).

[0148] Figures 2 to 5 The liquefier tube 5 of the first example is manufactured by providing a tubular body 50 having a substantially constant wall thickness t and a substantially circular cross-section. The tubular body 50 is deformed or extruded at locations defined by segments 53a to 53d in order to provide an inlet portion 51 and a first end portion 57 for receiving filament material (not shown) having a substantially circular cross-section and to provide a non-circular portion 53 formed by segments 53a to 53d, each segment having a non-circular cross-section. A substantially continuous transition is provided between each segment 53a to 53d.

[0149] In this example, the deformation or extrusion of the tubular body 50 is achieved by pressing the tubular body 50 at discrete points along the length of the tubular body using a press.

[0150] The extrusion tip 55 is connected to the tubular body 50 at the other end 52 opposite the inlet portion 51 to form an outlet for dispensing filament material in a molten state. In this example, the extrusion tip 55 is welded to the tubular body 50.

[0151] Reference is now made to Figures 6 to 9 , which show a liquefier tube 105 for use in a manufacturing system 1 for additive manufacturing according to a further example of the application. The liquefier tube 105 according to this example is similar to the liquefier tube 5 according to the first example, wherein similar features will be denoted by similar reference numerals increased by “100”. Figure 1 The liquefier tube 105 according to this example comprises a tubular body 150 providing a passageway P extending along the tubular body, and a wall thickness t of a side wall of the tubular body extending along the longitudinal axis L and being substantially constant (in particular, as shown more clearly in

[0152] Figure 9 ​The liquefier tube 105 is made of metal, in particular stainless steel, as is the liquefier tube 5 (see Figure 1) of the first example. The liquefier tube 105 is made of a tubular body 150 having a substantially circular cross-section.

[0153] The first end of the liquefier tube 105 upstream of the inlet portion 151 is provided with a first end portion 157 having a substantially circular cross-section. The second end 152 of the liquefier tube 105, downstream of the inlet portion 151, is also provided with a substantially circular cross-section. The first end portion 157 and the second end 152 are located at opposite ends of the tubular body 150.

[0154] Intermediate the first end portion 157 and the second end 152 is a first non-circular portion 153 having a non-circular cross-section, in this example in the form of an oblong cross-section. The first non-circular portion 153 is similar to the non-circular portion 53 of the liquefier tube 5 and extends uninterruptedly along a portion of the length of the tubular body 150 and has a substantially constant cross-sectional area. A second end portion 154 having a substantially circular cross-section extends along a portion of the length of the tubular body 150 between the second end 152 and the second non-circular portion 158.

[0155] In this example, similar to the non-circular portion 53 of the liquefier tube 5, the first non-circular portion 153 has 4 discrete segments: a first segment 153a, a second segment 153b downstream of the first segment 153a, a third segment 153c downstream of the second segment 153b, and a fourth segment 153d downstream of the third segment 153c. Each of the segments 153a to 153d is arranged consecutively along the longitudinal axis L of the first non-circular portion 153.

[0156] Downstream of the first non-circular portion 153, between the first non-circular portion 153 and the second end 152 is a second non-circular portion 158. The second non-circular portion 158 is similar to the first non-circular portion 153 but is rotated by 90 degrees.

[0157] The second non-circular portion 158 is similar to the non-circular portion 53 of the liquefier tube 5 and extends uninterruptedly along a portion of the length of the tubular body 150 and has a substantially constant cross-sectional area. A second end portion 154 having a substantially circular cross-section extends along a portion of the length of the tubular body 150 between the second end 152 and the second non-circular portion 158.

[0158] In this example, similar to the first non-circular portion 153, the second non-circular portion 158 has 4 discrete segments: a first segment 158a, a second segment 158b downstream of the first segment 158a, a third segment 158c downstream of the second segment 158b, and a fourth segment 158d downstream of the third segment 158c. Each of the segments 158a to 158d is arranged consecutively along the longitudinal axis L of the second non-circular portion 158.

[0159] Between the first non-circular portion 153 and the second non-circular portion 158 is a transition point or transition zone T at which the orientation of the non-circular portions of the liquefier tube 105 rotates by 90 degrees.

[0160] The tubular body 150 is deformed by extrusion to provide the first non-circular portion 153 and the second non-circular portion 158. In this example, each of the segments 153a-153d and each of the segments 158a-158d corresponds to an extrusion point / zone at which the tubular body 150 is deformed. A substantially continuous transition is provided between each of the segments 153a-153d and each of the segments 158a-158d and between the first non-circular portion 153 and the second non-circular portion 158 via the transition point or transition zone T.

[0161] The tubular body 150 includes a continuous transition when viewing the non-circular cross-section of the first segment 153a downstream from the substantially circular cross-section of the inlet portion 151. In this example, the cross-sectional area at the inlet portion 51 is substantially equal to the cross-sectional area of the first segment 153a.

[0162] Each of the segments 153a-153d and each of the segments 158a-158d has a major axis dimension Ml and a minor axis dimension M2. When viewed downstream from the inlet portion 151 toward the second end 152, within the first non-circular portion 153, the major axis dimension Ml increases while the minor axis dimension M2 decreases. At the fourth segment 153d, the major axis dimension Ml reaches its maximum value and the minor axis dimension M2 reaches its minimum value. The same is true for the second non-circular portion 158 when viewed from the transition point or transition zone T toward the second end 152.

[0163] In this example, the respective first segments 153a, 158a, the respective second segments 153b, 158b, the respective third segments 153c, 158c, and the respective fourth segments 153d, 158d correspond to one another in terms of cross-sectional shape but are rotated by 90 degrees. Thus, the major axis dimension Ml and the minor axis dimension M2 correspond to one another in each of these respective segments but are rotated by 90 degrees.

[0164] Throughout the first non-circular portion 153 and the second non-circular portion 158, the minor axis dimension M2 is less than the diameter of the inlet portion 151 and the diameter of the second end 152. Thus, when compared to the substantially circular cross-section of the inlet portion 151 and the substantially circular cross-section of the second end 152, the minimum distance from the sidewall of the tubular body 150 to the center of the passageway P is reduced in the first non-circular portion 153 and the second non-circular portion 158.

[0165] Downstream of the fourth section 158d, the second non-circular portion 158 transitions from a non-circular cross-section to a second end portion 154 having a substantially circular cross-section at the downstream end 152. The second end portion 154 extends along a portion of the length of the tubular body 150 between the second non-circular portion 158 and the downstream end 152.

[0166] As with the liquefier tube 5, the length of the circumference formed by the tubular body 150 in the first and second non-circular portions 153, 158 is greater than the length of the circumference at the first and second end portions 157, 154. This provides a greater contact area between the tubular body 150 and the filament (not shown) and thus increases the rate of heat transfer.

[0167] The second end 152 is provided with an extrusion tip 155 in the form of a nozzle for dispensing the filament material (not shown) in a molten state. The extrusion tip 155 provides an outlet for the liquefier tube 105 and has a substantially circular passage 156 extending along the liquefier tube (in particular, as shown in Figure 9 In this example, the extrusion tip 155 is welded to the tubular body 150 at the second end 152. As shown most clearly in Figure 9 The circular passage 156 of the extrusion tip 155 has a cross-sectional area that is less than the cross-sectional area of the passage of the tubular body 150.

[0168] In use, as with the liquefier tube 5, the liquefier tube 105 is received within the extrusion head 4 of the extrusion process-based additive manufacturing system 1 (in particular, as shown in Figure 1 The substantially circular cross-section of the inlet portion 151 is configured to receive filament material having a circular cross-section from the feed mechanism 6 in use.

[0169] The filament material is advanced along the tubular body 150. A heating means H, in this example in the form of one or more heating elements, is located within the extrusion head 4 and adjacent to the liquefier tube 105. The one or more heating elements are configured to heat the outer surface of the liquefier tube 105 which in turn heats the filament material as it is advanced due to heat transfer.

[0170] As the filament material is advanced from the inlet portion 151 towards the first non-circular portion 153, the filament material melts due to the heating. The cross-sectional shape of the filament material then conforms to the cross-sectional shape of the first non-circular portion 153.

[0171] In the first non-circular portion 153, the distance of the heating means H to the centre of the passage P, and thus to the centre of the filament material or to the filament flow path, is reduced, allowing heat to reach the centre of the filament material more efficiently. This allows for more efficient heat transfer.

[0172] Then, the filament advances from the first non-circular portion 153 toward the second non-circular portion 158 via the transition point or transition zone T. The rotational deflection of the first non-circular portion 153 and the second non-circular portion 158 causes mixing of the filament material, thereby improving heat transfer.

[0173] The extrusion pressure is generated by the upstream filament feed. The molten filament is extruded from the extrusion tip 155 and onto the printing platen 2 (specifically, as shown in the image). Figure 1 (as shown in the image).

[0174] In this example, Figures 6 to 9 The liquefier tube 105 is manufactured by providing a tubular body 150 having a substantially constant wall thickness t and a substantially circular cross-section. The tubular body 150 is deformed or compressed in a first direction at locations defined by segments 153a to 153d to provide an inlet 151 and a first end 157 having a substantially circular cross-section for receiving filament material (not shown), and to provide a first non-circular portion 153 formed by segments 153a to 153d, each segment having a non-circular cross-section. A substantially continuous transition is provided between each of the segments 153a to 153d.

[0175] Downstream of the first non-circular segment 153, the tubular body 150 is deformed or compressed in a second direction deflected by 90 degrees from the first direction. The tubular body 150 is deformed or compressed in the second direction at a location defined by segments 158a to 158d to provide a transition point or transition zone T and a second end 152 having a substantially circular cross-section.

[0176] In this example, the deformation or extrusion of the tubular body 150 is achieved by pressing the tubular body 150 at discrete points along the length of the tubular body using a press.

[0177] The extrusion tip 155 is connected to the tubular body 150 at its opposite end 152, opposite the inlet 151, to form an outlet for dispensing material in the molten state. In this example, the extrusion tip 155 is welded to the tubular body 150.

[0178] Now for reference Figures 10 to 12 These figures illustrate another example of the invention for use in... Figure 1 The liquefier tube 205 used in manufacturing system 1.

[0179] The liquefier pipe 205 has a similar profile to the liquefier pipe 105; however, unlike the passage P formed by the tubular body 150, this passage is partially formed by the split heater block 7. The split heater block 7 has two halves 7a, 7b (specifically, as shown in the image). Figure 10Each half 7a, 7b defines half of the passageway P of the liquefier tube 205.

[0180] The halves 7a, 7b are configured to be secured together to form the split heater block 7 and the liquefier tube 205. In this example, the halves 7a, 7b are configured to be secured together using bolts (not shown) and are each made of metal.

[0181] In this example, the first non-circular portion 253, the transition point or region T and the second non-circular portion 258 form a first element A of the liquefier tube 205 and are formed by the halves 7a, 7b. The inlet portion 251 and the first end portion 257 form a second element B of the liquefier tube 205 separate from the first element A. The second end 252, the second end portion 254 and the extrusion tip 255 form a third element C separate from the first element A and the second element B.

[0182] The second element B is secured by a threaded connection (not shown) to a threaded aperture formed in the first end 70 of the split heater block 7. Similarly, the third element C is secured by a threaded connection (not shown) to a threaded aperture formed in the second end 71 of the split heater block 7.

[0183] The first half 7a includes a cylindrical heater barrel 71a that includes a wire 72a extending therefrom. The second half 7b includes a temperature sensor 71b that includes a wire 72b extending therefrom. Each of the cylindrical heater barrel 71a and the temperature sensor 71b are located proximate the first element A and extend along the overall length of the heater block 7 from the first end 70 to the second end 71 (in particular, as shown in FIG. 3). Figure 12

[0184] The temperature sensor 71b and the heater barrel 71a, together with a controller (not shown), allow closed loop feedback control of the temperature via the respective wires 72a, 72b.

[0185] In use, the heater barrel 71a is configured to provide heat around the entire circumference of the liquefier tube 205 (in particular, the first element A) by conduction of the metal material of the halves 7a, 7b.

[0186] To assemble the liquefier tube 205 of FIG. 3, in this example, bolts (not shown) are used to secure each half 7a, 7b together. The two halves 7a, 7b form the first element A. Figures 10 to 12 The second element B is screwed into a threaded aperture formed in the first end 70 and the third element C is screwed into a threaded aperture formed in the second end 71.

[0187]

[0188] ​​As with the liquefier tube 5 and 105, the liquefier tube 205 is configured to be received within the extrusion head 4 of the extrusion-based additive manufacturing system 1 (in particular, as shown in Figure 1 the substantially circular cross-section of the inlet portion 251 is configured to receive, in use, filament material having a circular cross-section from the feed mechanism 6.

[0189] The filament material is advanced along the tubular body 250. The heating means H in the form of a heater barrel 71a of cylindrical shape transfers heat through the material of the first half 7a to the filament. The heater barrel 71a heats the filament material as it is advanced along the entire length of the heater block 7. The temperature output by the heater barrel 71a is controlled via the closed loop feedback controller described above.

[0190] The effect on the filament material as it is advanced along the liquefier tube 205 is similar to the case of the liquefier tube 105, and for the sake of brevity will not be described further. In this example, the heater block 7 begins heating the filament material upstream of the first non-circular portion 253, so that the polymer of the filament material begins to liquefy before it has to change shape.

[0191] In this example, Figures 10 to 12 the liquefier tube 205 is provided by providing a pair of metal blocks, or by providing a single metal block and separating it into two blocks, and machining the profile of the first element A into the planar surface of each half, thereby providing the halves 7a, 7b.

[0192] The second element B is formed by providing a tubular body and forming threads along a portion of the tubular body. The third element C is formed in a similar manner to the second element B, with the additional step of welding the extrusion tip 255 to the free end of the third element C to form an outlet for dispensing material in a molten state.

[0193] Reference is now made to Figures 13 to 16 which show a liquefier tube 305 for use in an additive manufacturing system 1 according to another example of the application. Figure 1

[0194] The liquefier tube 305 is similar to the liquefier tube 5, and like features will be indicated by like reference numerals each increased by "300".

[0195] The liquefier tube 305 differs from the liquefier tube 5 in the cross-sectional profile in the non-circular portion 353.

[0196] ​The first end of liquefier tube 305 upstream of the inlet portion 351 is provided with a substantially circular cross-section. The second end 352 of the liquefier tube 305 downstream of the inlet portion 351 is also provided with a substantially circular cross-section. The inlet portion 351 and the second end 352 are located at opposite ends of the tubular body 350.

[0197] Intermediate the inlet portion 351 and the second end 352 is a non-circular portion 353 having a non-circular cross-section.

[0198] In the present example, the non-circular portion 353 has 6 discrete segments: a first segment 353a, a second segment 353b downstream of the first segment 353a, a third segment 353c downstream of the second segment 53b, a fourth segment 353d downstream of the third segment 353c, a fifth segment 353e downstream of the fourth segment 353d, and a sixth segment 353f downstream of the fifth segment 353e. Each of the segments 353a to 353f is arranged continuously along the longitudinal axis L of the tubular body 350.

[0199] From the inlet portion 351 towards the second end 352, the cross-sectional profile of the tubular body 350 is gradually deformed such that the tubular body has a cross-shape or a cross shape at the fourth segment 353d. From the fourth segment 353d towards the second end 352, the cross-sectional profile of the tubular body has a gentle or continuous transition towards a substantially circular profile at the second end 352 and the second end portion 354. In the non-circular portion 353, the distance from the heating means H (in particular, as shown in Figure 1 the centre of the passage P is reduced, thus the distance of the heating means to the centre of the filament material or filament flow path is reduced, allowing heat to more effectively reach the centre of the filament material.

[0200] Furthermore, the cross or cross shape profile provides a smaller flow area (in particular, as more clearly shown in Figure 16 the passage P, allowing heat to more effectively transfer into the filament material conveyed along the passage P. The restriction of the flow area, especially in the fourth segment 353d, also manipulates the filament material, thus promoting mixing.

[0201] The progression of the filament material in use is similar to the description above in relation to the liquefiers 5, 105 and 205, and for the sake of brevity will not be described further.

[0202] In the present example, Figures 13 to 16The liquefier tube 305 is provided by a tubular body 350 having a substantially constant wall thickness t and a substantially circular cross-section. The tubular body 350 is deformed or extruded at locations defined by segments 353a to 353f so as to provide an inlet portion 351 and a first end portion 357 having a substantially circular cross-section for receiving the filament material (not shown), and a non-circular portion 353 formed from the segments 353a to 353f, each segment having a non-circular cross-section. A substantially continuous transition is provided between each of the segments 353a to 353f.

[0203] In the present example, the deformation or extrusion of the tubular body 350 is achieved by using a press to press the tubular body 50 at discrete points along the length of the tubular body. In particular, in the present example, the tubular body 350 is deformed by using a punch and die or a pressure brake.

[0204] Reference is now made to Figures 17 to 21 which show a liquefier tube 405 for use in a manufacturing system 1 for producing a Figure 1 according to another example of the present application.

[0205] The liquefier tube 405 is similar to the liquefier tubes 5, 105, 205 and 305, and like features will be indicated by like reference numerals each increased by "400".

[0206] The liquefier tube 405 differs from the liquefier tubes described above in that the flow path or passage P formed has a constant hydraulic diameter D H . The hydraulic diameter is defined by the equation:

[0207] D H = 4A / P

[0208] where D H is the hydraulic diameter, A is the flow area, and P is the perimeter defined by the tubular body 450.

[0209] The hydraulic diameter D H allows a pipe having a non-circular cross-section to be approximated as circular for the purposes of calculating pressure drop and fluid flow rate. Having the liquefier tube 405 with a constant hydraulic diameter D H provides a substantially constant pressure as the filament material progresses in use.

[0210] Thus, in the case of the liquefier tube 405, the change in cross-sectional shape in the non-circular portion 453 allows heat to be more efficiently transferred to the filament material as it is progressing, but at the same time does not increase the pressure applied to generate a given flow rate.

[0211] The first, upstream end of liquefier tube 405 is provided with an inlet portion 451 having a substantially circular cross-section. The second, downstream end 452 of liquefier tube 405, opposite inlet portion 451, is also provided with a substantially circular cross-section. Inlet portion 451 and second end 452 are located at opposite ends of tubular body 450.

[0212] Intermediate inlet portion 451 and second end 452 is a non-circular portion 453 having a non-circular cross-section. First end portion 457, second end portion 454 and non-circular portion 453 have a constant hydraulic diameter D H .

[0213] In this example, non-circular portion 453 has 4 discrete segments: a first segment 453a, a second segment 453b downstream of first segment 453a, a third segment 453c downstream of second segment 453b and a fourth segment 453d downstream of third segment 453c. Each of segments 453a to 453d is arranged continuously along longitudinal axis L of tubular body 450.

[0214] When viewing the non-circular cross-section of first segment 453a downstream from the substantially circular cross-section of inlet portion 451, tubular body 450 comprises a continuous transition. In this example, the cross-sectional area at inlet portion 451 is substantially equal to the cross-sectional area of first segment 453a.

[0215] Similar to liquefier tube 5, each of segments 453a to 453d has a major axis dimension Ml and a minor axis dimension M2. When viewed downstream from inlet portion 451 towards second end 452, major axis dimension Ml increases while minor axis dimension M2 decreases. At fourth segment 453d, major axis dimension Ml reaches its maximum value and minor axis dimension M2 reaches its minimum value.

[0216] Throughout non-circular portion 453, minor axis dimension M2 is less than the diameter of inlet portion 451 and the diameter of second end 452. Thus, when compared to the substantially circular cross-section of inlet portion 451 and the substantially circular cross-section of second end 452, the distance from the side wall of tubular body 450 to the centre of passage P is reduced in non-circular portion 453.

[0217] Downstream of fourth segment 453d, non-circular portion 453 transitions sharply from the non-circular cross-section to second end portion 454 having a substantially circular cross-section at second end portion 452.

[0218] In this example, Figures 17 to 21The liquefier tube 405 can be manufactured in a similar manner to the liquefier tube 205 described above, i.e. by providing a pair of metal blocks, or a single metal block and separating it into two blocks, and machining the profile of one half of the passage P into the planar surface of each half, so as to provide two halves that form the passage P when joined together.

[0219] As an alternative, the liquefier tube 405 can be manufactured by providing a metal sheet and performing a hydroforming process to form one half of the tubular body 450. Then, the pair of halves are attached to each other to form the tubular body 450.

[0220] As another alternative, the liquefier tube 405 can be manufactured by performing a hydroforming process on the tubular body 450. Deforming the tubular body 450 by hydroforming can include placing the tubular body 450 between a pair of dies and injecting a fluid under pressure into the passage P. The fluid under pressure causes the tubular body 450 to deform so that it conforms to the profile defined by the forming tool or the pair of dies and forms the non-circular portion 453.

[0221] The extrusion tip 455 is connected to the tubular body 450 at the other end 452 opposite the inlet portion 451 to form an outlet for dispensing the material in a molten state. In the present example, the extrusion tip 455 is welded to the tubular body 450.

[0222] It will be appreciated by the skilled person that various changes to the above examples are envisaged without departing from the scope of the present application. For example, the non-circular portion of the tubular body need not have a long circular cross-section. Rather, the non-circular portion can have any other suitable non-circular cross-section, e.g. a rectangular, star-shaped, oval, square, ovate, regular polygon, irregular polygon, simple convex polygon or simple concave polygon, etc.

[0223] Although the tubular member is described as being made of metal, in particular stainless steel, this need not be the case. Rather, the tubular member can be made of brass, copper, tungsten, titanium, molybdenum, beryllium copper or any other suitable metal or alloy.

[0224] Alternatively, the tubular member can be made of a polymeric material, e.g. a thermally conductive polymeric material.

[0225] Although the transition from the substantially circular inlet portion or change to the non-circular portion is described as being continuous, the skilled person will appreciate that this need not be the case. Rather, the transition can comprise a segmented, discrete and / or stepped transition.

[0226] In these examples, the extrusion tip or nozzle can be removably connected to the liquefier tube or tubular body. As described above, instead of welding, the extrusion tip or nozzle can be soldered to the liquefier tube or tubular body.

[0227] The non-circular portion 53 is described as having a taper along a portion of the length of the tubular body 50. Alternatively, the non-circular portion of the tubular body can include a plurality of segments or sections. Each segment or section of the plurality of segments or sections can include a deformed or extruded segment of the tubular body. Each segment or section of the plurality of segments or sections can be arranged, for example, continuously, along the length or major axis of the liquefier tube or tubular body. Each segment or section of the plurality of segments or sections can be arranged along the longitudinal axis of the liquefier tube or tubular body.

[0228] Each segment or section of the plurality of segments or sections (hereinafter: segment) can have, for example, a different cross-sectional shape, configuration, or cross-sectional profile from one another. One segment of the plurality of segments (e.g., a first segment) can have a different cross-sectional shape, configuration, or cross-sectional profile from another segment of the plurality of segments (e.g., a second segment).

[0229] In some examples, the first and second segments, for example, their major and / or minor axis dimensions, are rotationally deflected or skewed from one another. The first and second segments can be skewed or curved from one another or with respect to one another. The first and second segments can include a skew angle defined therebetween. The first segment can include a portion of the tubular body deformed or extruded in a direction skewed or rotationally deflected with respect to the second segment.

[0230] The respective minor and / or major axis dimensions of the first and second segments can be rotationally deflected or skewed from one another.

[0231] Although the non-circular portion 53 is described as being uninterrupted, this is not the case. Rather, the tubular body 50 can have a substantially circular portion between two or more segments of the non-circular portion.

[0232] It will also be understood by those skilled in the art that any number of combinations of the above-described features and / or features shown in the drawings provide significant advantages over the prior art and, as such, these combinations are within the scope of the application described herein.

Claims

1. A liquefier for use in an additive manufacturing system based on an extrusion process, the liquefier formed with a passageway having an inlet portion and an outlet portion downstream of the inlet portion, wherein the inlet portion has a substantially circular cross-section for receiving a filament material, wherein, The passage transitions from the inlet portion to a non-circular portion downstream of the inlet portion, the passage includes a substantially circular portion at or toward the outlet, and the non-circular portion or a segment of the non-circular portion flares or opens toward the substantially circular portion, the non-circular portion having a non-circular cross-section.

2. The liquefier of claim 1, wherein, The non-circular cross-section of the non-circular portion or a segment or segments thereof is star-shaped.

3. The liquefier of claim 1 or claim 2, wherein, The transition from the substantially circular portion to the non-circular portion or a segment or segments of the transition includes a continuous transition, a gradual transition, and / or a tapered transition.

4. The liquefier of claim 1 or claim 2, wherein, The transition from the substantially circular portion to the non-circular portion or a segment or segments of the transition includes a segmented transition, a discrete transition, and / or a stepped transition.

5. The liquefier of claim 1 or claim 2, wherein, The non-circular portion includes a major axis dimension and a minor axis dimension, and the minor axis dimension decreases along a portion of the length of the non-circular portion and flares or opens toward the outlet.

6. The liquefier of claim 1 or claim 2, wherein, The inlet portion, the substantially circular portion, and the non-circular portion of the passage, or segments thereof, have substantially equal cross-sectional areas.

7. The liquefier of claim 1 or 2, wherein, The non-circular portion includes a plurality of segments, each of the segments having a different cross-sectional shape or configuration.

8. The liquefier of claim 7, wherein, The passage includes a substantially circular portion between a first segment and a second segment.

9. The liquefier of claim 1 or claim 2, comprising a tubular body having a substantially constant wall thickness.

10. The liquefier of claim 1 or claim 2, wherein, The outlet includes an extrusion tip for dispensing material in a molten state.

11. The liquefier of claim 1 or claim 2, wherein, The liquefier is made of metal.

12. A liquefier assembly for use in an additive manufacturing system based on an extrusion process, the liquefier assembly comprising: The liquefier of any one of claims 1 to 11; and a heating element for heating filament material received in use in the liquefier.

13. An additive manufacturing system comprising the liquefier of any one of claims 1 to 11 or the liquefier assembly of claim 12.

14. A method of manufacturing a liquefier for use in an additive manufacturing system based on an extrusion process according to any one of claims 1 to 10, the method comprising: providing a tubular body having a substantially constant wall thickness and a substantially circular cross-section; deforming the tubular body or extruding the tubular body at a location spaced from one of the two ends of the tubular body to provide an inlet portion having a substantially circular cross-section, a non-circular portion having a non-circular cross-section downstream of the inlet portion, and a substantially circular portion downstream of the non-circular portion, wherein the inlet portion is for receiving filament material, the non-circular portion is downstream of the inlet portion.

15. A method of manufacturing a liquefier for use in an additive manufacturing system based on an extrusion process according to any one of claims 1 to 10, the method comprising: providing a first block of material to machine a first portion of a liquefier tube in a surface of the first block; providing a second block of material to machine a second portion of a liquefier tube in a surface of the second block; and joining the first block and the second block together to form a passage of the liquefier tube.

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