A heating unit for heating and melting a filament material

Abstract

A heating unit (100) for heating and melting a 3D printable material (110) for deposition in an additive manufacturing process is provided. The heating unit comprises a body (120) comprising an internal feed channel (130). The internal feed channel comprises an input (220) and an output (230), and the internal feed channel further comprises at least one channel portion (140) arranged between the input and the output. Each of the at least one channel portion (140) comprises a first straight channel section (150) and at least two second straight channel sections (160), the first straight channel section and each second straight channel section being joined end-to-end to form a channel intersection, and wherein, for each channel portion, there is a kink (180) between the first straight channel section and each second straight channel section, the kink having a kink angle, α, in a range of 70 to 110 degrees.

Description

[0001] 2024PF80164

[0002] 1

[0003] A HEATING UNIT FOR HEATING AND MELTING A FILAMENT MATERIAL

[0004] FILED OF THE INVENTION

[0005] The present invention generally relates to the field of 3D printing. More specifically, the present invention relates to a heating unit for a 3D printing apparatus.

[0006] BACKGROUND OF THE INVENTION

[0007] Additive manufacturing, sometimes also referred to as 3D printing, refers to processes used to synthesize a three-dimensional object. 3D printing is rapidly gaining popularity because of its ability to perform rapid prototyping without the need for assembly or molding techniques to form the desired article.

[0008] By using a 3D printing apparatus, articles or objects may be built in three dimensions in a number of printing steps that are usually controlled by a computer model. For example, a sliced 3D model of the object may be provided in which each slice is recreated by the 3D printing apparatus in a discrete printing step. The 3D printing apparatus may deposit successive layers of an extrudable material from a dispenser, and the layers may be cured or otherwise hardened after deposition, e.g. using a laser to induce the curing process. An example of such a 3D printing apparatus is disclosed in US 2010 / 0327479 Al.

[0009] The most widely used additive manufacturing technology is the process known as Fused Deposition Modeling (FDM). FDM is an additive manufacturing technology commonly used for modeling, prototyping, and production applications. FDM works on an "additive" principle by depositing material in layers. Other terms for FDM are "fused filament fabrication" (FFF) or "filament 3D printing" (FDP), which are considered to be equivalent to FDM. In general, FDM printers use a thermoplastic filament, which is heated to its melting point and then extruded, layer by layer, (more specifically filament after filament) to create a three-dimensional object.

[0010] The thermoplastic filament is typically heated by a heating unit comprising a body with heating elements and a straight channel through which the filament is fed. During the feeding of the filament material, from the input towards the output, the filament melts and can thereafter be extruded out of a nozzle. 2024PF80164

[0011] 2

[0012] Currently there is a desire for shortening the printing time by increasing the speed of printing, thereby reduce the cost of printing. This makes the FDM technique more competitive. In order to shorten the printing time, it is desirable to increase the output of the molten material coming out of the nozzle of the printer. However, there is a limit to the rate of how much material a heating unit can melt, i.e. the mass of filament material which is fed through and molten per unit time by the heating unit.

[0013] It has been demonstrated that it is possible to increase the molten material output by increasing the length of the flow channel. For a heating unit comprising a straight flow channel, this would require a longer heating unit. Alternatively, as in AU2022200413 Al, the use of a spline-shaped flow channel allows for the extension of the heating unit in two further directions when achieving the longer flow channel. In either case, increasing the length of the flow channel brings with it an undesired increase in size of the heating unit. This is disadvantageous due to the confinement of the space where heating units are usually installed. Further to this, larger heating units are associated with higher costs in their manufacturing. In turn, this puts a limit on how much of an increase in material output one can achieve by increasing the length of the flow channel.

[0014] Accordingly, there is a need for technology which even further increases the material output in FDM printers.

[0015] SUMMARY OF THE INVENTION

[0016] It is an object of the present invention to mitigate the above problems and to provide a heating unit for FDM printers, wherein the material output may be increased without increasing the size of the heating unit in the same extent of the prior art.

[0017] This and other objects are achieved by providing a heating unit having the features in the independent claims. Preferred embodiments are defined in the dependent claims.

[0018] According to a first aspect of the present invention, there is provided a heating unit for heating and melting a 3D printable material for deposition in an additive manufacturing process, wherein the heating unit comprises a body comprising an internal feed channel. The internal feed channel comprises an input for the 3D printable material and an output for molten 3D printable material, a direction, F, from the input to the output being a flow direction. The internal feed channel further comprises at least one channel portion 2024PF80164

[0019] 3 arranged between the input and the output, wherein each of the at least one channel portion comprises a first straight channel section and a number of second straight channel sections, the first straight channel section and each second straight channel section being joined end- to-end. For each channel portion, there is a kink between the first straight channel section and at least one of the second straight channel sections, the kink having a kink angle, a, in a range of 70 to 110 degrees.

[0020] According to a second aspect of the invention, there is provided a 3D printer comprising a heating unit according to the first aspect of the invention.

[0021] According to a third aspect of the invention, there is provided a method for manufacturing an object by means of an additive manufacturing process using the 3D printer according to the second aspect of the invention.

[0022] Thus, the present invention is based on the idea of providing a heating unit having a high molten material output rate by having an internal feed channel comprising one or more channel portions each defining at least one kink. The presence of the at least one kink impinges the feed of 3D printable material which has the surprising effect of rendering a face-on contact between the 3D printable material and the wall(s) of the internal feed channel. It has been found that this face-on contact is a more effective way of heating the 3D printable material compared to the unobstructed feed through the feed channels of the prior art.

[0023] It will be appreciated that the mentioned advantages of the heating unit of the first aspect of the present invention also hold for the 3D printer according to the second aspect of the present invention as well as for the method according to the third aspect of the present invention.

[0024] The present invention is advantageous in that the heating unit may achieve high molten material output rates without relying solely on the length of the internal feed channel. Thereby, the heating unit of the present invention may be designed smaller than a heating unit comprised in the art, which output rate relies solely on the length of the internal feed channel. Accordingly, the heating unit according to the present invention does not suffer from the size limitations of these prior art solutions, thereby enabling even higher molten material output rates in FDM-applications than what is available via prior art solutions.

[0025] The heating unit for heating and melting a 3D printable material for deposition in an additive manufacturing process comprises a body comprising an internal feed channel. 2024PF80164

[0026] 4

[0027] By the term “3D printable material”, it is here meant a material which can be extruded, e.g. a plastic material. For example, in embodiments, the 3D printable material is a thermoplastic material such as polycarbonate (PC), polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), polyethylene (PE), polypropylene (PP), acrylonitrile butadiene styrene (ABS), polystyrene (PS). The body of the heating unit is comprised of a thermally conductive material, typically a metal or metal alloy. Non limiting examples of the metal or metal alloy include brass, bronze, copper, aluminum or steel.

[0028] The internal feed channel comprises an input for the 3D printable material and an output for molten 3D printable material, and a direction, F, from the input to the output being a feed direction. In other words, the internal feed channel fluidly connects the input and the output. The input may be provided with one or more elements arranged or configured to guide (feed) the 3D printable material into the heating unit. Similarly, the output may be provided with one or more elements arranged or configured for controlled deposition (extrusion) of the molten 3D printable material outputted from the output, e.g. a nozzle.

[0029] The internal feed channel further comprises at least one channel portion arranged between the input and the output, wherein each of the at least one channel portion comprises a first straight channel section and a number of second straight channel sections, the first straight channel section and each second straight channel section being joined end- to-end. By the term “channel portion”, it is here meant any portion of the internal feed channel comprising two or more straight channel sections which are joined end-to-end. By the use of the term “end-to-end”, it is here meant to emphasize that any two or more ends of the straight channel sections are joined together at one common point or junction. Accordingly, a channel portion comprising two or more second straight channel sections joined end-to-end with a first straight channel section would constitute a channel intersection. By the use of the term “intersection” it is here meant a junction, or a manifold, wherein the internal feed channel divides into a plurality of channels, or wherein a plurality of channels merge into one. Correspondingly, a channel portion comprising one second straight channel portion joined end-to-end with the first straight channel portion would not constitute a channel intersection.

[0030] For each channel portion, there is a kink between the first straight channel section and at least one of the second straight channel sections, the kink having a kink angle, a, in a range of 70 to 110 degrees. Preferably, the kink angle, a, is in a range of 80 to 100 2024PF80164

[0031] 5 degrees, more preferably 85 to 95 degrees, most preferably 88 to 92 degrees, e.g. 90 degrees. By the term “kink”, it is here meant an abrupt change in the direction of the internal feed channel resulting from two straight channel sections joined end-to-end and having an angle relative to one another in the range of 70 to 110 degrees. The presence of the kink in the at least one channel portion promotes a more direct contact between the 3D printable material and the wall(s) of the internal feed chamber, thereby achieving a more effective heating of the 3D printable material. The more effective heating thereby obtained allows for a higher molten material output rate to be achieved without necessarily having a longer internal feed channel.

[0032] According to an embodiment of the present invention, the number of second straight channel sections may be at least two, wherein the first straight channel section and each second straight channel sections are joined end-to-end to form a channel intersection, and wherein the kink angle, a, is between the first straight channel section and each second straight channel section. Hence, a kink is defined between the first straight channel section and each of the number of second straight channel sections. The present embodiment is advantageous in that a greater number of kinks are defined wherein each kink contributes to a more effective heating of the 3D printable material. Further to this, the present embodiment is also advantageous in that the resistance to the feed of the 3D printable material in each of the branching second straight channel section is indifferent with regard to their angular relationship with the first straight channel section. Thereby an equal amount of heating of the 3D printable material in the branching second straight channels is ensured.

[0033] According to an embodiment of the present embodiment, the number of second straight channel sections may be in a range of two to five. Hence, the heating unit may comprise two, three, four, or five second straight channel sections. Accordingly, a channel intersection may branch into two, three, four or five straight channel sections. The present embodiment is advantageous as such a branching of the internal feed channel increases the total surface contact between the 3D printable material and the heating unit, thereby rendering a more effective heating of the 3D printable material.

[0034] According to an embodiment of the present invention, the at least one channel portion may be a plurality of channel portions. The present embodiment is advantageous since a combination of a plurality of channel portion results in an internal feed channel comprising a greater number of kinks, which even further increase the direct face-on contact 2024PF80164

[0035] 6 between the 3D printable material and the wall of the internal feed channel. Consequently, an even more efficient heating of the material is achieved.

[0036] According to an embodiment of the present invention, one or more of the channel portions may have a shape chosen from the group of an L-shape, a T-shape, a Z- shape, and a U-shape. By “L-shape”, it is herein meant a channel portion comprising a first straight channel section joined end-to-end with one second straight channel section, in so defining one kink. By “T-shaped”, it is here meant a channel portion comprising a first straight channel section joined end-to-end with two second straight channel sections, in so defining at least one kink. By “Z-shaped”, it is here meant a channel portion comprising a first and a second L-shaped channel portion wherein the second straight channel section of the first L-shaped portion constitutes the first straight channel section of the second L-shaped portion and wherein the second L-shaped portion is inverted relative to the first L-shaped portion along its first straight channel section. By “U-shaped”, it is here meant a channel portion comprising a first and a second L-shaped channel portion wherein the second straight channel section of the first L-shaped portion constitutes the first straight channel section of the second L-shaped portion and wherein the second L-shaped portion is inverted relative to the first L-shaped portion along its second straight channel section. The present embodiment is advantageous in that the channel portion(s) may have many different shapes whilst still having a kink to provide the advantages thereof.

[0037] According to an embodiment of the present invention the plurality of channel portions may comprises a pair of channel portions, wherein, in the direction, F, from the input to the output, the pair of channel portions comprises an upstream channel portion and a downstream channel portion, and wherein the upstream channel portion and the downstream channel portion comprise an equal number of second straight channel sections. The present embodiment is advantageous in that any branching of the internal feed channel into a number of second straight channel section by the upstream channel portion may later (downstream) be merged together into one single internal feed channel by the downstream channel portion. In other words, by pairing an upstream channel portion with a downstream channel portion comprising an equal number of second straight channel sections as the upstream channel portion, it is assured that the single input and a single output of the heating unit can be maintained. 2024PF80164

[0038] 7

[0039] According to an embodiment of the present invention, each second straight channel section of the upstream channel portion may be joined end-to-end with a respective second straight channel section of the downstream channel portion. Accordingly, in the present embodiment, the branches (second straight channel sections) of the branching upstream channel portion may be joined directly to the branches (second straight channel sections) of the merging downstream channel portion. The skilled person will realize that, each end-to-end joining between an upstream and downstream second straight channel portion may define a kink. Accordingly, said end-to-end join of the two second straight channel sections constitutes a channel portion on its own, wherein the second straight channel section of the upstream channel portion may be considered as a first straight channel section in that channel portion or vice versa. The present embodiment is advantageous as it results in a number of disruptions (kinks) to the feeding of the 3D printable material, as well as a branching into a number of second straight channel sections all the while utilizing a small space.

[0040] According to an embodiment of the present invention, each second straight channel section of the upstream channel portion may be joined end-to-end with a respective second straight channel section of the downstream channel portion via a respective third straight channel section. The present embodiment is advantageous as it allows each branch of the internal feed channel to have a longer extension through the body of the heating unit prior to its merging via the downstream channel portion. Furthermore, according to embodiments, the second straight channel sections of the downstream channel portion may converge into a (single) first straight channel section.

[0041] According to an embodiment of the present invention, in the direction, F, from the input to the output, the internal feed channel may comprise an input channel portion, the input channel portion being a first channel portion downstream of the input, wherein the input channel portion has an input first straight channel section and a number of input second straight channel sections, and wherein the input first straight channel section has a first length in a range of 1 to 8 cm, and each of the input second straight channel sections has a second length in a range of 1 to 8 cm, such as 2 to 4 cm. The present embodiment is advantageous as the defined length of the input first straight channel section assures that the 3D printable material is sufficiently heated, so as to be sufficiently malleable, before encountering the first 2024PF80164

[0042] 8 kink of the internal feed channel which is defined by the end-to-end joining between the input first straight channel section and the input section straight channel section.

[0043] According to an embodiment of the present invention, for at least one channel portion, the first straight channel section may be longer than each associated second straight channel section.

[0044] According to an embodiment of the present invention, at least one of the diameter of the internal feed channel is in a range of 2 to 8 mm, a length, L, of the internal feed channel, between the input and the output, is at least 1.5 times a length dimension, LD, of the heating unit, wherein the length dimension, LD, is in a range of 3 to 30 cm, and each of the first straight channel section and the second straight channel sections is in a range of 1 to 10 cm, is fulfilled. Hence, the diameter of the internal feed channel is in a range of 2 to 8 mm, a length, L, of the internal feed channel, between the input and the output, is at least 1.5 times a length dimension, LD, of the heating unit, wherein the length dimension, LD, is in a range of 3 to 30 cm, and / or each of the first straight channel section and the second straight channel sections is in a range of 1 to 10 cm.

[0045] According to an embodiment of the present invention, the body of the heating unit may further comprises a heating element arranged to heat the 3D printable material. By “heating element”, it is hereby meant substantially any element, unit, device, or the like, which is arranged or configured to heat the 3D printable material. The present embodiment is advantageous in that the heating element may be adaptively selected depending on the 3D printable material.

[0046] According to an embodiment of the present invention, the heating element may be arranged to heat, in the direction, F, from the input to the output, at least one upstream straight channel, U, being one of the first straight channel section and the number of second straight channel sections, to a first channel section temperature, Tl. At least one downstream straight channel, D, is one of the first straight channel section and the number of second straight channel sections, to a second channel section temperature, T2. The at least one upstream straight channel is arranged upstream from the at least one downstream straight channel. For at least one channel portion, the second channel section temperature, T2, is lower than the first channel section temperature, Tl. Hence, one or more upstream straight channels, U, is (are) or constitutes the first straight channel section or the second straight channel section(s), and one or more downstream straight channels, D, is (are) or constitutes 2024PF80164

[0047] 9 the first straight channel section or the second straight channel section(s), wherein the upstream straight channel(s) is arranged upstream from the downstream straight channel(s). Furthermore, for at least one channel portion, the second channel section temperature, T2, is lower than the first channel section temperature, Tl, i.e. T2 < Tl. Preferably, the temperature difference, i.e. T1-T2, is at least 5 degrees or at least 10 degrees, but e.g. not more than 30 degrees.

[0048] According to an embodiment of the present invention, there is provided an 3D printer comprising the heating unit according to any one of the previously described embodiments. The present embodiment is advantageous in that the heating unit according to the present invention is particularly suitable for 3D printers. The present embodiment is further advantageous in that the heating unit is compatible with many types of 3D printers, thereby providing an improved versatility and customization. Optionally, the 3D printer may further comprise a feeder configured to feed the filament, i.e. by application of a force on the filament. The 3D printer may optionally comprise a controller (of the feeder) configured to control a printing speed of the 3D printer (and accordingly the force applied by the feeder to the filament to force it into the internal feed channel). According to embodiments, the printing speed obtained by the 3D printer comprising the heating unit may be at least 0.5 kg / h, more preferably at least 1.5 kg / h, an most preferred at least 2 kg / h. It will be appreciated that the mentioned printing speeds may be obtained with the diameter(s) of the internal feed channel described in the detailed description.

[0049] According to an embodiment of the present invention, there is provided a method for manufacturing an object by means of an additive manufacturing process using the 3D printer according to the previously described embodiment. According to embodiments, the object may be an optical component, such as a part of a lamp or part of a luminaire.

[0050] Further objectives of, features of, and advantages with, the present invention will become apparent when studying the following detailed disclosure, the drawings and the appended claims. Those skilled in the art will realize that different features of the present invention can be combined to create embodiments other than those described in the following. 2024PF80164

[0051] 10

[0052] BRIEF DESCRIPTION OF THE DRAWINGS

[0053] This and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing embodiment(s) of the invention.

[0054] Fig. l is a schematic view of a heating unit according to an exemplifying embodiment of the present invention,

[0055] Figs. 2-9 are schematic views of channel portions according to exemplifying embodiments of the present invention,

[0056] Fig. 10 is a schematic view of a heating unit according to an exemplifying embodiment of the present invention,

[0057] Fig. 11 schematically shows a 3D-printing apparatus according to an embodiment of the present invention, and

[0058] Fig. 12 is a schematic flow chart diagram of a method according to an exemplifying embodiment of the present invention.

[0059] DETAILED DESCRIPTION

[0060] The heating unit according to the invention described will now be described in more detail with reference to the drawings.

[0061] Fig. 1 shows an embodiment of the heating unit 100 for heating and melting a 3D printable material for deposition in an additive manufacturing process. The heating unit 100 comprises a body 120 comprising an internal feed channel 130.

[0062] The body 120 of the heating unit 100 is comprised of a thermally conductive material, typically a metal or alloy. Non limiting examples of the metal or alloy include brass, bronze, copper, aluminum or steel.

[0063] The internal feed channel 130 comprises an input 220 for 3D printable material and an output 230 for molten 3D printable material. Each of the input 220 and the output 230 defines an opening in the body 120 of the heating unit 100. The input 220 may be provided with one or more elements (not shown) arranged or configured to guide (feed) 3D printable material into the heating unit 100. The element(s) arranged or configured to guide (feed) the 3D printable material into the heating unit 100 is (are) selected based on the form the 3D printable material. For example, if the 3D printable material is in the form of a filament, an element arranged or configured to feed said filament with appropriate and sufficient force into the input 220 is selected. Similarly, should the 3D printable material be 2024PF80164

[0064] 11 in the granular form, an element arranged or configured to feed said granules with appropriate and sufficient force into the input 220 is selected. The skilled person realizes that an element suitable for the feeding of 3D printable material in the filament form may not be suitable for the feeding of 3D printable material in the granular form. Elements for feeding 3D printable materials of various forms are well known to the skilled person as such, hence no further details are given here.

[0065] The output 230 may be provided with one or more elements arranged or configured for controlled deposition (extrusion) of molten 3D printable material outputted from the output, e.g. a nozzle.

[0066] The internal feed channel 130 fluidly connects the input 220 and the output 230, wherein a direction, F, from the input 220 to the output 230 is a feed direction of the 3D printable material.

[0067] The internal feed channel 130 comprises at least one channel portion arranged between the input 220 and the output 230. Figs. 2-8 show different embodiments of channel portions 140 from which the internal feed channel may be comprised according the inventive concept of the present invention. By the term “channel portion”, it is here meant any portion of the internal feed channel comprising two or more straight channel sections 150, 160 which are joined end-to-end. By the use of the term “end-to-end”, it is here meant to emphasize that any two or more ends of the straight channel sections 150, 160 are joined together at one common point or junction. The channel portions 140 shown in Figs. 2-8 have in common that each channel portion 140 comprises a first straight channel section 150 and a number of second straight channel sections 160, the first straight channel section 150 and each second straight channel section 160 being joined end-to-end. For each channel portion, there is a kink 180 defined between the first straight channel section 150 and at least one of the second straight channel sections 160. By the term “kink”, it is here meant an abrupt change in the direction of the internal feed channel resulting from two straight channel sections 150, 160 joined end-to-end and having an angle relative to one another in the range of 70 to 110 degrees. By the presence of the kink 180 in the at least one channel portion 140 comprising the internal feel channel, a more direct contact between the 3D printable material and the wall(s) of the internal feed chamber is promoted. The more effective heating thereby obtained allows for a higher molten material output rate to be achieved without necessarily having a longer internal feed channel. Each kink 180 in the embodiments shown in Figs. 2-8 has a kink 2024PF80164

[0068] 12 angle, a, in a range of 70 to 110 degrees. It should be noted that the internal feed channel ultimately may be comprised of any number and combination of the channel portions 140 according to Figs. 2-8.

[0069] The heating unit 100 has a length, L, a width, W, and a depth, D, whereby the length, L, is the largest dimension. In embodiments, the length, L, may be in a range of 3 to 30 cm, preferably in a range of 4 to 20 cm, and even more preferred in a range of 5 to 15 cm. In embodiments, the relation between the length, L, width, W, and depth, D, may fulfill L > D > 0.2L and / or L > W > 0.2L.

[0070] In embodiments, the length of the internal feed channel 130 between the input 220 and the output 230 is at least 1.5 times, more preferably at least 2 times, more preferably 3 times, an even more preferred at least 4 times the length, L, of the heating unit 100. The diameter of the internal feed channel 130 may be in a range of 2 to 8 mm.

[0071] Fig. 2 shows an example of a channel portion 140 according to the invention comprising one first straight channel section 150 joined end-to-end with one second straight channel section 160, whereby at their end-to-end joining, there is defined a kink 180 having a kink angle, a, in a range of 70 to 110 degrees. Accordingly, the angle, a, between the first straight channel section 150 and the second straight channel section 160 is in the range of 70 to 110 degrees. The shape of this example channel portion 140 is L-shaped. Accordingly, such channel portions will be referred to as L-shaped channel portions in this text.

[0072] Fig. 3 shows another example of a channel portion 140 according to the invention wherein the number of second straight channel sections 160 are two. Accordingly, the present embodiment comprises one first straight channel section 150 joined end-to-end with two second straight channel sections 160. In the present example, each of the two second straight channel sections 160 defines an angle, a, relative to the first straight channel section 150 which is in the range of 70 to 110 degrees. In so, each end-to-end joining between the second straight channel sections and the first straight channel section 150, defines a respective kink 180 having a kink angle, a, in a range of 70 to 110 degrees. In other embodiments comprising two second straight channel sections 160, only one of the two second straight channel sections 160 may form an angle, a, relative to the first straight channel section 150 which is within the range of 70 to 110 degrees. In such embodiments only one kink 180 is defined. Embodiments comprising two second straight channel sections 2024PF80164

[0073] 13

[0074] 160, such as the embodiment shown in Fig. 3, is T-shaped, accordingly, such channel portions 140 are referred to as T-shaped channel portions in this text.

[0075] Fig. 4 shows an example of a channel portion 140 according to the invention wherein the number of second straight channel sections 160 is two or more. The present embodiment comprises three second straight channel sections 160, although it should be noted that channel portions comprising three, four or five second straight channel sections are possible. In embodiments where the number of second straight channel sections 160 is at least two, the first straight channel section 150 and each second straight channel section 160 are joined end-to-end to form a channel intersection wherein the (respective) kink angle, a, is between the first straight channel section 150 and each second straight channel section 160. Hence, in these embodiments, a kink 180 is defined between the first straight channel section 150 and each of the number of second straight channel sections 160. The two or more second straight channels sections 160 joined end-to-end with the first straight channel section 150 may extend therefrom such that their extensions lie within one common plane of extension. Alternatively, their extensions may be such that none of the two or more second straight channel sections 160 share a plane of extension. A channel portion 140 comprising two or more second straight channel sections 160 joined end-to-end with a first straight channel section 150, such as (but not limited to) a T-shaped channel portion, constitutes a channel intersection. Accordingly, the channel intersection may branch into two, three, four or five second straight channel sections. By the use of the term “intersection” it is here meant a junction, or a manifold, wherein the a first straight channel section 150 (internal feed channel) divides into a plurality of channels (second straight channel sections 160), or wherein a plurality of second straight channel sections 160 merge into one internal feed channel (first straight channel section 150). Such a branching of the internal feed channel increases the total surface contact between the 3D printable material which is to be molten and the heating unit, i.e. the walls of the internal feed channel. Correspondingly, a channel portion (not shown) comprising one first straight channel portion joined end-to-end with one second straight channel portion, such as a L-shaped channel portion, would not constitute a channel intersection.

[0076] Next, Figs. 5 and 6 show examples of channel portions according to the present invention wherein the at least one channel portion of the feed channel is a plurality of channel portions, wherein one or more of the channel portions has a Z-shape or a U-shape. 2024PF80164

[0077] 14

[0078] By combining a plurality of channel portions 140, an internal feed channel comprising a greater number of kinks can be achieved which even further increases the direct face-on contact between the 3D printable material and the wall of the internal feed channel.

[0079] Fig. 5 shows a “Z-shaped” channel portion, which can be appreciated to be a channel portion 140 comprising a first and a second L-shaped channel portion, LI, L2, wherein the second straight channel section 160 of the first L-shaped portion, LI, constitutes the first straight channel section 150 of the second L-shaped portion, L2, and wherein the second L-shaped portion, L2, is inverted relative to the first L-shaped portion, LI, along its first straight channel section 150.

[0080] Fig. 6 shows a “U-shaped” channel portion, which also can be appreciated to be a channel portion 140 comprising a first and a second L-shaped channel portion, LI, L2 wherein the second straight channel section 160 of the first L-shaped portion, LI, constitutes the first straight channel section 150 of the second L-shaped portion, L2, and wherein the second L-shaped portion, L2, is inverted relative to the first L-shaped portion, LI, along its second straight channel section 160.

[0081] Next, Figs. 7 and 8 show other examples of channel portions according to the present invention. The at least one channel portion of the feed channel is a plurality of channel portions, wherein the channel portion comprises a pair of channel portions, and wherein, in the direction, F, from the input to the output, the pair of channel portions comprises an upstream channel portion and a downstream channel portion, and wherein the upstream channel portion and the downstream channel portion comprise an equal number of second straight channel sections. Accordingly, any branching of the internal feed channel into a number of second straight channel sections by the upstream channel portion may later (downstream) be merged together into one single internal feed channel by the downstream channel portion. In other words, by pairing an upstream channel portion with a downstream channel portion comprising an equal number of second straight channel sections as the upstream channel portion, it is assured that a single input and a single output of the heating unit can be maintained.

[0082] Fig. 7 shows a channel portion 140 according to an example, wherein each pair of channel portions 140u, 140d comprises two or more second straight channel sections 160. Each second straight channel section 160 of the upstream channel portion 140u is joined end- to-end with a respective second straight channel section 160 of the downstream channel 2024PF80164

[0083] 15 portion 140d. Accordingly, in such embodiments, the branches (second straight channel sections) of the branching upstream channel portion 140u are joined directly to the branches (second straight channel sections) of the merging downstream channel portion 140d. The skilled person will realize that each end-to-end joining between an upstream and downstream second straight channel portion 160 may on its own define a kink 180. Accordingly, said end- to-end join between the two second straight channel sections 160 may constitutes a channel portion, i.e. an L-shaped channel portion, in accordance with embodiments previously described. Hence, the second straight channel section 160 of the upstream channel portion 140u may be considered as a first straight channel section in that channel portion or vice versa.

[0084] Fig. 8 shows an alternative of the embodiment described in Fig. 6, wherein each second straight channel section 160 of the upstream channel portion 140u is joined end- to-end with a respective second straight channel section 160 of the downstream channel portion 140u via a respective third straight channel section 170. Accordingly, each branching from the upstream channel portion 140u may have a longer extension through the body of the heating unit prior to its merging via the downstream channel portion 140d.

[0085] Fig. 9 shows a further example of a channel portion according to the present invention wherein the at least one channel portion of the feed channel 130, in a direction, F, from the input 220 to the output 230, is an input channel portion 140i. The input channel portion 140i is a first channel portion downstream of the input 220. Worded differently, the input channel portion 140i is the first channel portion of the feed channel 130 as seen in the direction, F, from the input 220 to the output 230. The input channel portion 140i has an input first straight channel section 150 and a number of input second straight channel sections 160. The input first straight channel section 150 is directly joined to the input 220 of the heating unit 100 at one of its ends. Alternatively, a first end of the input first straight channel section 150 may be said to define the input 220 of the heating unit 100. The input first straight channel section 150 has a first length in a range of 5 to 8 cm, and each of the input second straight channel sections 160 has a second length in a range of 2 to 4 cm. In other words, the input first straight channel section 150 is longer than the input second straight channel section 160. Accordingly, embodiments of the heating unit according to the present invention comprising a input channel portion 140i can be said to comprise at least one channel portion wherein the first straight channel section 150 is longer than each associated second straight 2024PF80164

[0086] 16 channel section 160. The defined length of the (i.e. longer) input first straight channel section 150 assures that the 3D printable material is sufficiently heated, so as to be sufficiently malleable, before encountering the first kink of the internal feed channel which is defined by the end-to-end joining between the input first straight channel section 150 and the input second straight channel section 160.

[0087] Next, Fig 10 shown an embodiment of the heating 100 unit according to the present invention wherein the absolute dimensions, d, of the internal feed channel 130 is in the range of 2 to 8 mm, such as e.g. 2 to 4 mm. Fig. 10 further shows an embodiment wherein the body 120 of the heating unit 100 further comprises a heating element 200 arranged to heat the 3D printable material. By “heating element”, it is hereby meant substantially any element, unit, device, or the like, which is arranged or configured to heat the 3D printable material. In the present embodiment, the heating unit 100 is arranged to heat, in the direction, F, from the input 220 to the output 230, at least one upstream straight channel, U, being one of the first straight channel section, and the number of second straight channel sections, to a first channel section temperature, Tl. The heating unit 100 is further arranged to heat at least one downstream straight channel being one of the first straight channel section, and the number of second straight channel sections, to a second temperature, T2. The at least one upstream straight channel, U, is arranged upstream from the at least one downstream straight channel, D. For at least one channel portion 140, the second channel section temperature, T2, is lower than the first channel section temperature, Tl.

[0088] Fig. 11 schematically shows a 3D-printer 400 according to an embodiment of the present invention. The 3D-printing apparatus 400 comprises a heating unit according to any one of the preceding embodiments, which in turn comprise a body 120 comprising an internal feed channel 130 comprising at least one channel portion according to any one of the preceding embodiments.

[0089] Fig. 12 is a schematic flow chart diagram of a 3D-printing method for manufacturing an object by means of an additive manufacturing process using the 3D printer of the previous embodiment. The method comprises the step of providing 510 a heating unit comprising a body comprising an internal feed channel comprising at least one channel portion according to any of the preceding embodiments. The method further comprises the step of feeding 520 3D printable material into the input of the heating unit. The method further comprises the step of heating 530 the 3D printable material fed through the heating 2024PF80164

[0090] 17 unit toward its output. The method further comprises the step of outputting 540 (extruding) melted 3D printable material from the output of the heating unit.

[0091] The person skilled in the art realizes that the present invention by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. For example, it will be appreciated that the figures are merely schematic views of heating unit arrangements according to embodiments of the present invention. Hence, any elements / components of the heating unit 100 such as the exemplified channel portions, and the dimensions thereof, may have different dimensions, shapes and / or sizes than those depicted and / or described.

Claims

2024PF8016418CLAIMS1. A heating unit (100) for heating and melting a 3D printable material for deposition in an additive manufacturing process, wherein the heating unit (100) comprises a body (120) comprising an internal feed channel (130), wherein the internal feed channel (130) comprises an input (220) for the 3D printable material and an output (230) for molten 3D printable material, a direction, F, from the input (220) to the output (230) being a flow direction, wherein the internal feed channel (130) further comprises at least one channel portion (140) arranged between the input (220) and the output (230), wherein each of the at least one channel portion (140) comprises a first straight channel section (150) and at least two second straight channel sections (160), the first straight channel section (150) and each second straight channel section (160) being joined end-to-end to form a channel intersection, and wherein, for each channel portion (140), there is a kink (180) between the first straight channel section (150) and each second straight channel section (160), the kink (180) having a kink angle, a, in a range of 70 to 110 degrees.

2. The heating unit (100) according to claim 1, wherein the number of second straight channel sections (160) is in a range of two to five.

3. The heating unit (100) according to any one of the previous claims, wherein the at least one channel portion (140) is a plurality of channel portions (140).

4. The heating unit (100) according to claim 3, wherein the plurality of channel portions (140) comprises a pair of channel portions (140),2024PF8016419 wherein, in the direction, F, from the input (220) to the output (230), the pair of channel portions (140) comprises an upstream channel portion (140u) and a downstream channel portion (140d), and wherein the upstream channel portion (140u) and the downstream channel portion (140d) comprise an equal number of second straight channel sections (160).

5. The heating unit (100) according to claim 4, wherein each second straight channel section (160) of the upstream channel portion (140u) is joined end-to-end with a respective second straight channel section (160) of the downstream channel portion (140d).

6. The heating unit (100) according to claim 5, wherein each second straight channel section (160) of the upstream channel portion (140u) is joined end-to-end with a respective second straight channel section (160) of the downstream channel portion (140d) via a respective third straight channel section (170).

7. The heating unit (100) according to any one of the previous claims, wherein, in the direction, F, from the input (220) to the output (230), the internal feed channel (130) comprises an input channel portion (140i), the input channel portion ( 140i) being a first channel portion downstream of the input (220), wherein the input channel portion (140i) has an input first straight channel section (150) and a number of input second straight channel sections (160), and wherein the input first straight channel section (150) has a first length in a range of 1 to 8 cm, and each of the input second straight channel sections (160) has a second length in a range of 1 to 8 cm.

8. The heating unit (100) according to any one of the previous claims, wherein, for at least one channel portion (140, 140u, 140d, 140i), the first straight channel section (150) is longer than each associated second straight channel section (160).

9. The heating unit (100) according to any one of the previous claims, wherein one or more of the channel portions (140, 140u, 140d, 140i) has a shape chosen from the group of an L-shape, a T-shape, a Z-shape, and a U-shape.2024PF801642010. The heating unit (100) according to any one of the previous claims, wherein at least one ofThe diameter of the internal feed channel (130) is in a range of 2 to 8 mm, a length, L, of the internal feed channel (130), between the input (220) and the output (230), is at least 1.5 times a length dimension, LD, of the heating unit (100), wherein the length dimension, LD, is in a range of 3 to 30 cm, and each of the first straight channel sections (150) and the second straight channel sections (160) is in a range of 1 to 10 cm, is fulfilled.

11. The heating unit (100) according to any one of the previous claims, wherein the body (120) further comprises a heating element (200) arranged to heat the 3D printable material.

12. The heating unit (100) according to claim 11, wherein the heating element (200) is arranged to heat, in the direction, F, from the input (220) to the output (230), at least one upstream straight channel, U, being one of the first straight channel section (150), and the number of second straight channel sections (160), to a first channel section temperature, Tl, and at least one downstream straight channel, D, being one of the first straight channel section (150), and the number of second straight channel sections (160), to a second channel section temperature, T2, wherein the at least one upstream straight channel, U, is arranged upstream from the at least one downstream straight channel, D, and wherein, for at least one channel portion (140, 140u, 140d, 140i), the second channel section temperature is lower than the first channel section temperature.

13. A 3D printer (400) comprising the heating unit (100) according to any one of claims 1 to 12.2024PF801642114. A method for manufacturing an object by means of an additive manufacturing process using the 3D printer (400) according to claim 13.

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