Printing apparatus with screw device for material feed for additive manufacturing processes

Abstract

The present invention relates to a printhead for an additive manufacturing process, the printhead comprising a material feeding device having a material conveying screw designed or configured such that the screw and its drive can be inserted and replaced flexibly and economically efficiently. The invention also relates to a printing device for an additive manufacturing process comprising at least one printhead according to the invention.

Description

[0001] The present invention relates to a print head for an additive manufacturing process, the print head comprising a material feed device having a material conveying screw which is designed or configured such that the screw and its drive can be inserted and replaced flexibly and cost - effectively. The present invention also relates to a printing device for an additive manufacturing process, which comprises at least one print head according to the present invention.

[0002] Print heads and corresponding printing devices for additive manufacturing processes in which particulate starting materials are used are known from the prior art.

[0003] Such print heads typically comprise a print nozzle and means for feeding material into the print nozzle, which means typically has an extrusion screw (also referred to herein as a "material conveying screw"). Exemplary disclosures include US 2017 / 0008230A1 and the review article by Shaik et al. (2021) in Open Access Library Journal 8:e7698 on pellet extruders.

[0004] In additive manufacturing processes such as 2D and 3D printing (which typically involve computer - controlled positioning of the printing material on the printing table of a printing device), there are challenges, particularly in the field of pharmaceuticals and / or food supplements, in printing objects containing active ingredients, namely that a printing device aimed at achieving individualized supply of active ingredients should be as easy to set up as possible and have as low an operating cost as possible.

[0005] The technical problem to be solved by the present invention is to provide a print head and a printing device for an additive manufacturing process, which are inexpensive to manufacture in terms of material feeding and ensure a simple and variable supply of spare parts.

[0006] The above - mentioned technical problem is solved by the embodiments of the present invention disclosed in the claims, as well as in this specification and the drawings.

[0007] In particular, the present invention provides a print head for an additive manufacturing process, comprising:

[0008] - a print nozzle, and

[0009] - A material feeding device, the material feeding device having (i) at least one material conveying screw configured to feed particulate printing material into a printing nozzle by a rotational movement about its longitudinal axis, and (ii) at least one drive unit for the at least one material conveying screw, wherein the at least one material conveying screw has a proximal end driven by the drive unit and a distal end from which the printing material is conveyed to the printing nozzle, and wherein the at least one material conveying screw (5) has a standard thread or a self-tapping thread at least on a portion thereof including the distal end of the at least one material conveying screw.

[0010] The print head according to the present invention may include more than one printing nozzle and more than one material feeding device, each material feeding device having one of the material conveying screws and its drive unit as defined according to the present invention.

[0011] The print head of the present invention and further embodiments of the present invention are preferably configured for additive manufacturing by hot melt extrusion (HMT), more preferably for additive manufacturing by FDM (fused deposition modeling). Particularly preferably, the print head according to the present invention and further embodiments of the present invention are designed for additive manufacturing of pharmaceutical, nutraceutical and / or food supplement products, particularly dosage forms, more preferably oral dosage forms, preferably by FDM.

[0012] Preferably, the material conveying screw has a thread, i.e., a standard thread or a self-tapping thread, with a core diameter of 2.0 to 30 mm.

[0013] In a preferred embodiment, the proximal end of the material feeding screw has a shape and / or at least one groove for driving the material conveying screw by the drive unit.

[0014] The proximal end of the material conveying screw preferably includes a screw head which preferably has an average diameter larger than the outer diameter of other parts of the material conveying screw. More preferably, the screw head has a shape and / or at least one groove for driving the material conveying screw by the drive unit.

[0015] Preferably, the length of the thread or the total length of the material conveying screw or the length of the material conveying screw excluding the screw head (if present) is about 30 mm to about 100 mm, more preferably about 40 mm to about 90 mm.

[0016] In certain embodiments of the present invention, the end or end region of the material conveying screw opposite the screw head may be tapered or otherwise tapered, respectively. This is particularly preferred for self-tapping material conveying screw threads.

[0017] In a further preferred embodiment, the outer diameter of the thread (excluding any tapered or other tapered ends, if present) is from about 4.0 to about 5.0 mm. In certain embodiments, the core diameter of the thread can be from about 2.0 to about 4.0 mm. In a further preferred embodiment, the flank angle of the thread can be from about 30° to about 80°, preferably from about 55° to about 65°, and most preferably about 60°. In a further embodiment, the lead angle is from about 2° to about 50°, in other embodiments from about 5° to about 50°, and most preferably about 3°. In certain further embodiments of the present invention, the pitch of the thread is from about 0.4 mm to about 4.0 mm. In certain embodiments of the present invention, the thread can have a thread depth of from about 0.25 mm to about 3.0 mm. In a further embodiment, the thread width of the thread can be from about 0.1 mm to about 2.0 mm.

[0018] According to the present invention, the term "standard thread" refers to a substantially standardized thread whose parameters are governed by national or international standards. Preferably, the standard thread is selected from metric or imperial standard threads. Preferred standard threads correspond to the metric ISO standard threads according to the valid i.e. current version of DIN 13-1, preferably DIN 13-1 (1999-11). More preferably, the threads are selected from the sizes M2 to M20, in particular from M2, M2.5, M3, M3.5, M4, M4.5, M5, M5.5, M6, M7, M8, M9, M10, M11, M12, M13, M14, M15, M16, M17, M18, M19, M20, according to the valid i.e. current version of DIN 13-1, preferably DIN 13-1 (1999-11). In other embodiments of the present invention, the standard thread is the standard imperial thread according to the respective valid i.e. current version of ASME / ANSI B1.1, preferably according to ASME / ANSI-B1.1 1989 (R2003). More preferably, the threads are selected from the sizes #3-64 UNC, #4-40 UNC, #5-40 UNC, #6-32 UNC, #8-32 UNC, #10-24 UNC, #12-24 UNC, 1 / 4"-20 UNC, 5 / 16"-18 UNC, 3 / 8"-16 UNC, 7 / 16"-14 UNC, 1 / 2"-13 UNC, 9 / 16"-12 UNC, 5 / 8"-11 UNC, 3 / 4"-10 UNC, 7 / 8"-9 UNC, 1"-8 UNC, according to the respective valid i.e. current version of ASME / ANSI B1.1, preferably according to ASME / ANSI-B1.1 1989 (R2003). In other embodiments of the present invention, the thread can also be a Whitworth thread, preferably a Whitworth thread from 1 / 4" to 3 / 4".

[0019] In the case of a material conveying screw having self-forming threads (also known as self-tapping threads), it is preferred to use wood screw threads. The preferred wood screw threads for the present invention are also standardized wood screw threads, more preferably metric wood screw threads. Even more preferably, they are metric wood screw threads according to the currently valid, i.e., the latest version, of DIN 7988. Particularly preferred are the wood screw threads according to DIN 7988 (1975-2). In a particularly preferred embodiment, the wood screw threads are selected from H3 to H20, including H3, H3.5, H4, H4.5, H5, H5.5, H6, H7, H8, H10, H12, H16, H20, according to the respective currently valid, i.e., the latest version, of DIN 7988, and most preferably DIN 7988 (1975-2).

[0020] In a preferred embodiment of the present invention, the flanks of the threads of the material conveying screw, preferably the flanks of standard threads or self-tapping threads respectively, are configured such that the flanks do not have acute angles with each other at least at or near the positions where they intersect (i.e., at or near the positions where the flanks of the thread flanks intersect), at least on the outer side of the thread. Thus, compared to other material conveying screws that are basically the same, the ends of the flanks, i.e., the positions where the flanks of the flanks intersect or converge, are flattened and / or rounded at least in the region of the flank ends. This embodiment has the particular advantage of at least reducing, preferably substantially preventing, material wear or loss at the flank ends or at specific contact points between the flank ends (especially at or near the intersection of the flanks of the flanks) and the usually present feed housing or the feed screw channel that respectively houses the material conveying screw. The reduction or respectively avoidance of material wear preferably relates to the flank ends and / or the feed housing or feed channel that houses the material conveying screw, more preferably both. In this context, the reduction of material wear or loss means that compared to a material conveying screw (preferably other material conveying screws that are basically the same) that does not have flattened and / or rounded flank ends as described above, the material wear or loss is preferably reduced by at least about 30%, more preferably by at least about 40%, still more preferably by at least about 50%, even more preferably by at least about 60%, still at least more preferably by at least 70%, even more preferably by at least about 80%, yet more preferably by at least about 90%, and most preferably by at least about 95%. It is obvious to those skilled in the art that the percentage reduction of material wear and / or loss is set relative to the defined operating or usage cycles of the corresponding unit (the material conveying screw and / or the feed housing or feed channel that houses the material conveying screw therein) where material wear or material loss occurs. The corresponding time period can be selected, for example, as the defined number of operating hours or usage hours, such as about 10 hours, about 50 hours, about 100 hours, about 200 hours, or about 500 hours or more, such as about 1000 hours. In another embodiment, the reduction of material wear and / or material loss can also be determined relative to the objects printed by means of the print head or printing device of the present invention, by analyzing whether there is material originating from the conveying screw and / or the feed housing or feed channel in the printed objects, where the corresponding amount of worn or lost material is usually expressed as a mass unit per printed object, such as ng, μg, mg, or grams, or as a number of printed objects, such as about 100, about 200, about 500, or more objects, such as about 1000 or about 2000 or more objects.

[0021] In a preferred embodiment of this type, the flanks or the ends of the flanks of the standard thread or self-tapping thread are at least approximately trapezoidal, conical, or spherical, or are shaped in this way. Regarding the flanks of the trapezoidal thread, it is also preferred that the corners of the trapezoidal flanks (on the outer side) are rounded.

[0022] In a further preferred embodiment of the above type of the present invention, the standard thread of the material feed screw (5) is selected from M5 to M20 in accordance with DIN 158-1 (1997-06).

[0023] Regarding the design of the above-mentioned material conveying screw thread for reducing or preventing material wear and / or loss, especially at the flank of the thread and / or at the contact position with the feed housing or its channel for receiving the material conveying screw, those skilled in the art understand that, or the term standard thread or self-tapping thread is understood in this sense, that such a thread is also a standard or self-tapping thread, at least in terms of these threads, except for the rounded or flattened ends of the thread flanks, otherwise it is a self-tapping thread, at least in terms of these threads, except for the rounded or flattened ends of the thread flanks, otherwise it corresponds to, especially in terms of the parameters conforming to national or international standards, a conventional standard thread or self-tapping thread.

[0024] The reduction and even basic prevention of the above-mentioned material wear or loss is particularly important for the print head and / or printing device and / or kit according to the present invention for additive manufacturing (preferably by the additive manufacturing method according to the present invention) of pharmaceutical, nutraceutical and / or food supplement products (especially dosage forms, more preferably oral dosage forms), because such objects are administered to users, and according to the present invention, the contamination caused by such material wear and / or loss in such objects should be minimized or prevented as much as possible.

[0025] According to the present invention, it is preferred to use a standard screw as the material conveying screw, preferably having the thread as described in the previous paragraph, which combines particularly high availability and cost-effective price in the manufacture of the print head equipped in this way and in its maintenance. Such screws are available in large quantities and a wide variety in DIY stores. In the field of additive manufacturing of pharmaceutical and / or nutraceutical and / or food supplement products (especially dosage forms, more preferably oral dosage forms), the screw should be completely, at least in any case the part of the screw in contact with the printing material, that is, usually the threaded part of the material conveying screw, be composed of or contain high-quality steel that may be required for the production of pharmaceutical and / or nutraceutical and / or food supplement products. Examples of materials that can be used for the above applications are high-quality steels, such as V2A and V4A, and particularly preferred are steels of steel group numbers 1.43, 1.44 and 1.45 in accordance with the respective valid i.e. current version of DIN EN10027-1 / -2.

[0026] If the proximal end of the material screw has a screw head, the shape of the head of the material conveying screw is preferably selected from a lens head, a flat head, a countersunk head (including a lens countersunk head, a countersunk milled head and a trumpet head), a hexagon head, a round head (sometimes also called a semi-round head), a pan head and a cylinder head.

[0027] The selection of the material conveying screw, especially in terms of shape and thread, will depend on the type and size of the printing material to be used, such as pellets, granules or powders.

[0028] In a preferred embodiment, the drive shape, i.e., the way in which the proximal end of the material screw (preferably the screw head) is shaped, is such that the drive element of the drive unit can engage form - locked or drive - locked in the screw head (especially via suitable grooves in the screw head) or on the screw head (especially via the outer shape of the screw head), selected from external hexagonal socket, internal hexagonal socket, slotted, Phillips, Pozidriv, hexalobular internal socket (also known as Torx), Mortorq, Torx - Plus, LocTec and Secloc drives. A particularly preferred drive is the hexalobular internal or Torx, or Torx - Plus drive. In other embodiments of the material conveying screw according to the invention that do not have a screw head, the proximal end of the screw also has a drive part which is designed such that the drive unit engages form - locked or drive - locked at or in one or more grooves at the proximal end of the material conveying screw, or the shape of the proximal end (or the shape of the correspondingly designed proximal region of the material conveying screw) is configured such that the drive unit can engage form - locked or drive - locked with the proximal end or the proximal region of the material conveying region. In a preferred embodiment, the drive is preferably selected from external hexagonal socket, internal hexagonal socket, slotted, Phillips, Pozidriv, hexalobular internal socket (also known as Torx), Mortorq, Torx - Plus, LocTec and Secloc drives. A particularly preferred drive is the hexalobular internal or Torx, or Torx - Plus drive.

[0029] The drive unit of the print head according to the invention preferably has a drive element which engages form - locked or drive - locked with the proximal end of the material conveying screw, preferably with the screw head. Particularly preferably, the drive element is detachably connected to the drive unit, and more preferably, the drive element is detachably connected to the drive device by a replacement mechanism. Such an embodiment can be realized, for example, by a so - called bit which is detachably fixed in a corresponding socket of the drive device. Usually, such a bit is held in the socket by a spring element. In other embodiments, the replacement mechanism can also be provided by a clamping device such as a drill chuck or the like.

[0030] The print head according to the present invention preferably includes means for receiving the particulate printing material (preferably pellets, granules or powder) before it is fed to the material feeding device, and preferably also includes a structure or mechanism for feeding or introducing the printing material into the material feeding device. In certain embodiments, a funnel-shaped embodiment, usually provided with suitable closing and opening mechanisms, can be used. In other embodiments, a conveyor screw or auger can also be used to feed the printing material into the material feeding device in the case of a material container.

[0031] The print head according to the present invention, which is an extrusion print head in this example, includes other commonly used components for an additive manufacturing process, which is preferably characterized as an FDM (Fused Deposition Modeling) process in the context of the present invention, such as a print nozzle (also referred to as an extrusion nozzle). Another common component is a heating device, preferably provided upstream of the print nozzle, for heating the usually solid or semi-solid printing material into an extrudable form. In a preferred embodiment, the print head can also have a cooling mechanism, such as a heat sink, for dissipating or separately regulating the generated heat. A coolant can also be circulated in the cooling device that can be used according to the present invention.

[0032] The drive unit generally includes a motor, which can be designed as a stepper motor in certain embodiments. In other embodiments, the motor can also produce continuous motion. In any case, the drive unit ensures a rotational motion, which is transmitted to the material conveyor screw through a drive element. The drive unit is preferably configured such that it drives the material conveyor screw to rotate about its longitudinal axis at about 2 rpm to about 20 rpm, more preferably at about 2 rpm to about 12 rpm.

[0033] On the other hand, the present invention provides a kit or article, comprising

[0034] - at least one print head (1) for an additive manufacturing process, which includes a print nozzle (2) and a material feeding device configured to accommodate at least one material conveyor screw (5), and a drive unit (9) for the at least one material conveyor screw (5), and

[0035] - at least one material conveyor screw (5), which is configured to move the particulate printing material into the print nozzle (2) through a rotational motion about its longitudinal axis when the material conveyor screw is arranged in the material feeding device, the at least one material conveyor screw having a proximal end driven by the drive unit and a distal end from which the printing material is conveyed to the print nozzle (2) when the at least one material conveyor screw is arranged in the material feeding device,

[0036] wherein the at least one material conveyor screw (5) has a standard thread or a self-tapping thread at least on the part thereof including the distal end of the material screw.

[0037] Another kit of the present invention includes a print head in which a material delivery screw is arranged as defined, and at least one additional material delivery screw as defined according to the present invention, wherein the additional material delivery screw(s) can be the same or different, which is valid both for each other and for the material delivery screw(s) already arranged in the print head according to the present invention.

[0038] Therefore, the print head according to the present invention can also be provided as a kit (also referred to as an "article") together with one or more material delivery screws and / or together with one or more drive elements (preferably in the form of a bit), the drive elements being adapted to the drive type of the material delivery screw and being detachably connectable to a drive unit, preferably by a replacement mechanism.

[0039] The kit can include screws having the same or different threads and / or lengths and / or screw heads and / or drive types. Optionally, the kit can include the same or different drive elements adapted to the drive type of the material delivery screw.

[0040] As already elaborated in detail above, the kit according to the present invention can be designed such that at least one print head is already provided with a material screw arranged therein. Alternatively, as more specifically defined above, the kit includes at least one print head as described above without a material delivery screw arranged therein and at least one material delivery screw as described above, and this type of kit further includes one or more drive elements adapted to the drive type of the material delivery screw, wherein the drive elements (preferably in the form of a bit) can be detachably connected to a drive device, preferably by a replacement mechanism.

[0041] The preferred embodiments of the material delivery screw of the kit according to the present invention are as described above.

[0042] The present invention also relates to a printing device for an additive manufacturing process, comprising one or more print heads of the present invention and a printing bed including a printing table having a printing surface.

[0043] Furthermore, the printing device preferably includes further common elements and devices typical and / or advantageous for 2D and / or 3D printing devices. In particular, at least one print head and / or the printing table are movable by suitable, usually electric, servo motors such that the position of the print head (or group of print heads) or at least the print nozzles (or group of print nozzles) relative to the printing surface is changeable along the spatial axes x, y, and z.

[0044] In a preferred embodiment of the present invention, the printing device includes a unit for preferably automatically calibrating the position of the printing nozzles, in particular an optical device for capturing an image of the printing nozzles of the printing device. In this regard, reference is made to the disclosure of the document DE 20 2021 003 596 U1.

[0045] Preferably, the printing device of the present invention includes a computerized control unit configured to move and detect the position of at least the printing nozzles or groups of printing nozzles of the printing table and / or respectively the print head.

[0046] Furthermore, the printing device preferably includes a computerized image processing unit designed to display and process the image data of the printing nozzles generated by the optical device.

[0047] It is also preferred that the printing device includes a computer unit configured to correlate the image data of the computerized image processing unit and the position data of the computerized control unit. In particular, the computer unit is configured to measure and store the differences in position data at least in the x - y direction (i.e., horizontal position data), preferably also in the z direction (i.e., vertical position data).

[0048] In a preferred embodiment of the present invention, the printing device includes at least one device for analyzing an additive manufacturing process (in particular 2D and / or 3D printing) performed with the printing device and / or an object produced by means of the device.

[0049] Preferably, the printing device includes at least one device for performing a spectral measurement of the material applied to the printing surface. In a particularly preferred embodiment, the device is a device for infrared spectral measurement, more preferably a NIR (near - infrared) device. In other embodiments, a Raman spectroscopy device is used, where Raman spectroscopy and infrared spectroscopy (more preferably NIR spectroscopy) can be used simultaneously or successively. In this case, the device according to the present invention includes both a device for Raman spectroscopy and a device for infrared spectroscopy, more preferably for NIR spectroscopy.

[0050] In another embodiment of the present invention, each print head includes a device for measuring the flow rate of the material flowing into and / or through the print head or respectively through the printing nozzles. In a preferred embodiment, the flow rate is measured by a magnetic induction flow measurement unit. According to the present invention, the flow measurement device is preferably used in the printing devices of the present invention, which are particularly designed for 2D printing or at least respectively for 2D printing.

[0051] In another embodiment, the printing device includes a device, preferably an infrared thermal imager, for recording a thermal image of the material flowing out of the printing nozzle and / or the material applied to the printing surface.

[0052] In addition, the print head may include a device for inductive flow measurement.

[0053] In another preferred embodiment, the printing table includes a weighing device.

[0054] Preferably, the printing device according to the invention includes a preferably computerized device for recording, processing and monitoring the process data collected by means of the above-described process analysis devices. This device is also referred to hereinafter as the process monitoring device. In addition, and preferably, this computer-aided process monitoring device is connected to (preferably via a data exchange and / or data transmission and / or data reception device) the above-described computer-aided control, image processing and computer unit, such that the process parameters obtained by the process monitoring device can be integrated.

[0055] Typically, and preferably according to the invention, the method according to the invention is carried out in a computerized or computer-aided manner, particularly preferably using the computer-aided control and / or image processing and / or computer unit described in detail above.

[0056] An additive manufacturing method is also disclosed, preferably for 2D and / or 3D printing, for producing objects, preferably objects containing active agents, preferably pharmaceutical and / or health nutritional products and / or dietary supplement dosage forms, preferably for oral administration, the method comprising the step of printing particulate printing material such as pellets, granules and / or powders using a printing device according to the invention.

[0057] In addition, the printing method preferably uses one or more of the above-described devices for analyzing the manufacturing process.

[0058] A method for producing particulate printing material is also disclosed, preferably pellet, granule or powder printing material, which may be carried out prior to the additive manufacturing method in a preferred embodiment. Preferably, the printing material includes at least one pharmaceutical and / or at least one health nutritional product and / or at least one dietary supplement active ingredient, typically in at least one pharmaceutically acceptable and / or health nutritional product acceptable and / or dietary supplement compatible carrier.

[0059] The method for producing particulate printing material includes the following steps:

[0060] (a) Producing a filamentous printing material blank; and

[0061] (b) Crushing the printing material blank.

[0062] In a preferred embodiment, a filamentous printing material blank, also referred to herein as a printing material filament, is produced from starting substances or materials, respectively, by extrusion in a suitable manner, preferably by hot melt extrusion (HME). The particle size of the printing material to be produced can be determined at least two-dimensionally by choosing the diameter of the filament. The comminution can be carried out, for example, by cutting the blank. Of course, any mechanical or other comminution process can be selected and combined with each other. The process can also include a size selection or sorting step. For example, the material obtained can be screened according to the corresponding grain size after comminution. In a preferred embodiment, the comminution and sorting can also be carried out in combination, for example by filing screening, usually using commercially available equipment.

[0063] The invention is outlined in more detail below by way of exemplary, non-limiting embodiments with reference to the accompanying drawings:

[0064] Figure 1 A schematic front view of a print head according to the invention is shown. The relevant components of the print head (1) are described with reference to Figure 1 from the bottom (also referred to herein as "distant" relative to the end of the material feed screw connected to the drive unit) to the top (also referred to herein as "near" relative to the end of the material feed screw connected to the drive unit). The print head 1 of this embodiment has a print nozzle 2. Granular printing material, preferably pellets, granules or powder, is heated by a heating device 3 to convert the printing material into a flowable state. To prevent overheating of the system, the print head 1 is equipped with a cooling device 4, which preferably includes a heat sink through which a coolant flows, as shown in this embodiment with reference to Figure 1 FIG. The feed chamber 10 is arranged above the cooling device 4, which hides a part of the screw 5 in this view, whereby the printing material is fed into the screw chamber (also referred to as the conveying chamber or extrusion chamber) in this area, which can be achieved, for example, by a funnel-shaped construction usually provided with an opening / closing mechanism. The material feed screw 5 extends above the feed chamber 10, which can also serve as a guiding element for the screw 5 and is directly supported by a screw support 6 under the screw head, in which the screw 5 is centered directly under the screw head 5a (a countersunk head in this example) and can rotate about its longitudinal axis.

[0065] Figure 2Schematic side sectional view showing the basic elements of the print head 1 according to the invention. For clarity, the usually present housing is not shown. From the bottom (distant) to the top (near), the sectional view shows the printing nozzles, behind which (near) is the heating device 3. The respective distal or distal regions of the material conveying screw 5 are tapered and terminate at the transition to the heating device 3. The material conveying screw 5 extends in a conveying chamber (also denoted as extrusion chamber) which starts just above the heating device and extends distally (here: upwards) to the feed chamber 10. Above it (near) is the feed chamber 10 into which the printing material, preferably pellets, granules and / or powder, is fed by means of a dispensing device 7a. The screw 5 extends further upwards (near) through the feed chamber 10 and is supported at its upper (near) end region by a bracket 6 so as to be centered and rotatable about its longitudinal axis. In the present embodiment, the bracket 6 encloses a part of the thread and a part of the screw (countersunk) head 5a. In the shown embodiment, the dispensing device 7a, the feed chamber 10, the screw bracket 6 and the upper (near) part of the approximately conveying chamber (i.e., in the proximal direction behind the cooling device) are arranged in a feed housing 7. In addition to the screw head 5a, the material conveying screw 5 is provided with a self-tapping thread.

[0066] Figure 3 Schematic view showing the individual components of the print head according to the invention, in which the material conveying screw 5 including the Torx countersunk head 5a and the drive element including the Torx screw drive head 8a have not yet been inserted into the feed housing 7, as described above with reference to Figure 2 As mentioned, the dispensing device 7a, the feed chamber 10, the screw bracket 6 and the upper (near) part of the approximately conveying chamber (i.e., in the proximal direction above the cooling device) are arranged in the feed housing 7. The drive element 8 with the screw drive head 8a is designed as a screwdriver bit, enabling rapid change of the drive type and screw type.

[0067] Figure 4 Shows Figure 3 A further schematic view of the elements, in which the drive element 8 including the Torx drive head 8a is inserted into the drive unit 9.

[0068] Figure 5 Schematic view of the material conveying screw inserted into the conveying chamber located in the feed housing 7.

[0069] Figure 6 Shows as Figure 1 A further schematic view of the print head elements in the assembled state as shown. In particular, it can be seen how the Torx drive head 8a of the drive element 8 meshes in a shape - fitting manner with the corresponding Torx grooves of the countersunk head 5a of the material conveying screw 5.

[0070] Figure 7 shows an oral dosage form of metoprolol succinate printed using an embodiment of the present invention, which in this case is a two-sided planar object in the form of a tablet. (A) Top view of the printed tablet. (B) Side view of the printed tablet.

[0071] The present invention is further illustrated with reference to the following non-limiting examples.

[0072] Examples

[0073] Using the printing device according to the present invention, two different metoprolol succinate formulations (A and B) were printed in the form of tablets by FDM.

[0074] Both formulations were initially produced by three-stage tumbling mixing. Thereafter, they were prepared by hot melt extrusion from powdered raw materials using a laboratory extruder (ZE HM99, Three Tec GmbH, Sion, Switzerland) with a die diameter of 2 mm. The extrusion temperature for formulation A was 100 °C and for formulation B was 140 °C. The extruded strips were ground and sieved at 250 rpm using a U5

[0075] device (Quadro Engineering Corp., Waterloo, CA) to obtain particles with a diameter of 1 mm to 2 mm.

[0076] Table 1 below shows the composition of formulations A and B and their proportions (in wt%, based on the total weight of each formulation).

[0077]

[0078] MSN: Metoprolol succinate (medicinal active ingredient)

[0079] KVA64: Kollidon VA64 (vinylpyrrolidone - vinyl acetate copolymer; carrier polymer)

[0080] EPO: Eudragit E PO (anionic copolymer of methacrylic acid and methyl methacrylate; carrier polymer)

[0081] PEG: Lixopol 6000 (polyethylene glycol; plasticizer)

[0082] The parameters of the extrusion screw (material conveying screw) used are varied as shown in Table 2 below. The screw can handle both granules and powders.

[0083] Table 2: Parameters (range) of the extrusion screw used.

[0084]

[0085] Tablets are printed from the obtained particles by FDM using the print head of the present invention as a component of the printing device according to the present invention. The printing flux (printing volume per unit time) at the printing nozzle is 1.131 mm 3 / s, and the moving speed of the printing nozzle is 25 mm / s. The printing temperature varies between 140 °C and 160 °C. The printing surface temperature of the printing table is 50 °C. Exemplary dosage forms obtained by the printing process are as shown in Figure 7A (top view) and Figure 7B (side view).

[0086] List of reference numerals:

[0087] 1 Print head

[0088] 2 Print nozzle

[0089] 3 Heating device

[0090] 4 Cooling unit

[0091] 5 Material delivery screw

[0092] 5a Head

[0093] 6 Screw support

[0094] 7 Feed housing

[0095] 7a Dispensing device

[0096] 8 Driving element

[0097] 8a Screw drive head

[0098] 9 Driving unit

[0099] 10 Feed chamber

Claims

1. A print head for an additive manufacturing process, the print head comprising: - a print nozzle (2), and - a material feeding device having (i) at least one material conveying screw (5) configured to feed particulate print material into the print nozzle (2) by a rotational movement about its longitudinal axis, and (ii) at least one drive unit (9) for the at least one material conveying screw (5), wherein the at least one material conveying screw has a proximal end and a distal end, the proximal end being driven by the drive unit and the print material being conveyed from the distal end into the print nozzle (2), characterized in that the at least one material conveying screw (5) has a standard thread or a self-tapping thread at least on the part thereof that includes the distal end of the at least one material conveying screw.

2. The print head according to claim 1, wherein, The thread of the material conveying screw (5) has a core diameter of 2.0 mm to 30 mm.

3. The print head according to claim 1 or 2, wherein, The proximal end of the material conveying screw (5) has a shape and / or at least one groove configured to drive the material feeding screw (5) by the drive unit (9).

4. The print head according to any one of the preceding claims, wherein, The length of the thread of the material conveying screw (5) is 30 mm to 100 mm.

5. The printhead according to any one of the preceding claims, wherein, The standard thread of the material conveying screw (5) is selected from M2 to M20 in accordance with DIN 13-1 (1999-11).

6. The print head according to any one of claims 1 to 4, wherein, The self-tapping thread is a wood screw thread.

7. The print head according to claim 6, wherein, The wood screw thread of the material conveying screw is selected from H3 to H20 in accordance with DIN 7988 (1975-02).

8. A print head according to any one of the preceding claims, wherein, The flank of the standard thread or the self-tapping thread of the material feeding screw (5) is at least approximately trapezoidal, conical or spherical.

9. The print head according to any one of claims 1 to 4, wherein, The standard thread of the material feeding screw (5) is selected from M5 to M20 in accordance with DIN 158-1 (1997-06).

10. The print head according to any one of the preceding claims, wherein, The proximal end of the material conveying screw (5) includes a screw head (5a) having a shape and / or at least one groove adapted to drive the material feeding screw (5) by the drive unit.

11. The print head according to claim 10, wherein, The shape of the screw head (5a) is selected from a lens head, a pan head, a countersunk head, a square head, a hexagon head, a round head, a pot head and a cylinder head.

12. The print head according to any one of the preceding claims, wherein, The proximal end of the material screw conveyor (5), preferably the screw head (5a), has a drive type selected from external square, internal square, external hexagon, internal hexagon, slotted for a flat-blade screwdriver, slotted for a cross-blade screwdriver, Pozidriv, internal hexagon with a recessed cross, external hexagon with a recessed cross, Mortorq, Torx-Plus, LocTec and Secloc drive.

13. The print head according to any one of the preceding claims, wherein, The drive unit (9) includes a drive element (8) that respectively engages form-fittingly on or with the proximal end of the material feeding screw (5), preferably respectively engages on or with the screw head (5a).

14. The print head according to claim 13, wherein, The drive element (8) is detachably connected to the drive unit (9).

15. The print head according to claim 14, wherein, The drive element (8) is detachably connected to the drive unit (9) by means of a replacement mechanism.

16. The print head according to claim 15, wherein, The drive element (8) is designed as a bit and the drive device has a recess configured to receive the bit in a form-fitting manner.

17. A printing device for an additive manufacturing process, the printing device comprising: - one or more print heads (1) according to any one of the preceding claims; and - a printing bed, the printing bed comprising a printing table having a printing surface.

18. A kit, the kit comprising: - at least one print head (1) for an additive manufacturing process, the at least one print head (1) comprising a printing nozzle (2) and a material feed device adapted to receive at least one material feed screw (5), and a drive unit (9) for the material delivery screw (5), and - at least one material delivery screw (5), the at least one material delivery screw (5) being configured to feed particulate printing material into the printing nozzle (2) by a rotational movement about its longitudinal axis when the material delivery screw (5) is arranged in the material feed device, wherein, The material delivery screw (5) has a proximal end and a distal end, the proximal end being driven by the drive unit, and when the material delivery screw is arranged in the material feed device, the printing material is conveyed from the distal end into the printing nozzle (2); characterized in that The material delivery screw (5) has a standard thread or a self-tapping thread at least on the part thereof that includes the distal end of the material delivery screw (5).

19. A kit, the kit comprising: - at least one print head according to any one of claims 1 to 16, and - at least one material delivery screw (5), the at least one material delivery screw (5) being configured to feed particulate printing material into the print nozzle (2) by a rotational movement about its longitudinal axis when the material delivery screw (5) is arranged in the material feeding device, wherein, The material delivery screw (5) has a proximal end and a distal end, the proximal end being driven by a drive unit, and when the material delivery screw is arranged in the material feed device (9), the printing material is conveyed from the distal end into the printing nozzle (2); characterized in that A further material delivery screw (5) has a standard thread or a self-tapping thread at least on the part thereof that includes the distal end of the material delivery screw (5).

20. The kit according to claim 18 or 19, wherein, The material screw is defined according to any one of claims 2 to 12.

21. An additive manufacturing method, preferably for 2D and / or 3D printing, for manufacturing an object, the method comprising the step of printing a particulate printing material, preferably pellets, granules and / or powder, using the printing device according to claim 17.

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