Nozzle device for a print head for a 3D printer and method for operating a print head with a nozzle device

Abstract

The invention relates to a nozzle device (80) for a print head (100) for a 3D printer (150), wherein the nozzle device (80) is suitable for dispensing a liquid phase (12) of at least one printable material, and wherein the nozzle device (80) has an outlet opening (8) whose cross-section is variably adjustable to change the volume flow of the liquid phase (12). The invention is characterized in that the nozzle device (80) has two nozzle bodies (61, 62) arranged concentrically within one another, wherein the inner nozzle body (61) is arranged within a threaded sleeve (26) such that the inner nozzle body (61) is movable relative to the outer nozzle body (62) by rotating the threaded sleeve (26). Furthermore, the invention relates to a method for operating a print head (100) with a nozzle device (80) according to the invention.

Description

The present invention relates to a nozzle device for a print head for a 3D printer and to a method for operating a print head having a nozzle device according to the invention.Prior ArtA 3D printer for a variable viscosity material receives a solid phase of this material as a starting material, generates a liquid phase therefrom, and selectively applies this liquid phase to the sites associated with the object to be generated. Such a 3D printer comprises a print head in which the starting material is processed ready for printing. Furthermore, means are provided for generating a relative movement between the print head and the working surface on which the object is to be produced. In this case, either only the print head, only the working surface or else both the print head and the working surface can be moved.The printhead has a first operating state in which liquid material exits from it and a second operating state in which no liquid material exits from it. The second operating state is assumed, for example, when a different position on the work surface is approached and no material is to be discharged there on the way. A switch can be made between the two operating states of the print head, for example, by switching the advance of the solid starting material on or off.The most common is fused deposition modeling (FDM), in which a filament is melted from the starting material in an electrically heated extruder die and is applied layer by layer to a platform. In the form of such a filament, the starting material is very expensive.DE 10 2021 202649 A1 discloses a print head for a 3D printer, wherein a granulate is plasticized therein via a piston and a heated section. When the piston presses on the granulate, the granulate is compacted, thereby closing the nozzle of the print head.DE 10 2016 213439 A1 discloses a screw extruder with an adjustable nozzle, wherein the nozzle can change a volume flow from the nozzle.The object of the invention is to provide a nozzle device for a print head for a 3D printer and a method for operating a print head with a nozzle device, which permit an optimized printing process, wherein high-quality melt is to be provided in reproducible quality.Disclosure of the InventionIn the context of the invention, a nozzle device for a print head for a 3D printer and a method for operating a print head having a nozzle device according to the invention have been developed.The invention relates to a nozzle device for a print head for a 3D printer, wherein the nozzle device is suitable for dispensing a liquid phase of at least one printable material, wherein the nozzle device has an outlet opening, the cross section of which can be variably adjusted for changing a volume flow of the liquid phase.According to the invention, the nozzle device has two nozzle bodies arranged concentrically one inside the other, wherein the inner nozzle body is arranged within a threaded sleeve in such a way that the inner nozzle body can be moved relative to the outer nozzle body by rotation of the threaded sleeve. The cross section of the outlet opening of the nozzle device, or the nozzle cross section, is changed by the relative movement of the inner nozzle body to the outer nozzle body in such a way that the volume flow of the liquid phase, or of a melt, changes. The two nozzle bodies arranged one inside the other thus achieve that the print head can print with different volume flow depending on the setting, whereby a further print head can be advantageously dispensed with if a plurality of nozzle diameters would be necessary during a print job or printing process. During printing with a large opening cross section of the outlet opening of the nozzle device, the printing process can be accelerated, in particular when regions of the component to be printed have to be filled. The nozzle device according to the invention can avoid a nozzle change, whereby a reduction of the downtime by refitting is advantageously achieved. This shortens the printing process. In addition, the adjustment effort is reduced by a nozzle change of the print head.The component printed with the nozzle device of the print head can furthermore have better optics, since for example the outer contour of the component is printed by a smaller cross section of the outlet opening. A smaller cross section means a small nozzle diameter, or a smaller nozzle, respectively, whereby a high accuracy of printing is achieved. The larger cross section enables an increase in the material throughput and thus a faster filling of the component, whereby a faster filling of the component can be achieved with the same path position of the print head.Furthermore, by using the nozzle device, the component properties, such as strength, can be improved since a higher density can be achieved between the printed layers, or the layers, since the fill density is improved. Further, a print head having the nozzle device is made compact, whereby weight reduction of the print head can be achieved.In a further development of the invention, the threaded sleeve can be controlled by an actuator of the nozzle device.The threaded sleeve controlled by the actuator ensures the relative movement of the inner nozzle body with respect to the outer nozzle body, as a result of which the nozzle cross section changes and the volume flow of the liquid phase or of the melt thereby changes. The threaded sleeve provides the stroke and rotation of the inner nozzle body.In a further development of the invention, the outer nozzle body has a recess on its inner wall and the inner nozzle body has a lateral opening at the level of the recess of the outer nozzle body.In a further development, in a first operating state of the print head, the outlet opening of the nozzle device is formed by a nozzle opening of the inner nozzle body.This achieves a small nozzle diameter, as a result of which it is possible to print into fine outer contours which advantageously have improved optics.In a further development, in further operating states of the print head, the outlet opening of the nozzle device is formed by an opening cross section, wherein this results from the relative movement of the inner nozzle body to the outer nozzle body.This achieves a variable nozzle diameter, whereby wider contours can be printed if necessary, or regions of the component can be filled. As a result, the printing process can be advantageously accelerated.The invention further relates to a method for operating a print head having a nozzle device according to the invention.Further measures which improve the invention are described in more detail below together with the description of the preferred exemplary embodiments of the invention on the basis of figures.BRIEF DESCRIPTION OF THE DRAWINGThe following are shown: FIG. 1 is a cross-sectional view of a nozzle device according to the invention of a print head of a 3D printer; FIG. 2 shows a cross-sectional view in a side view of the nozzle device according to the invention in a first operating state; FIG. 3 shows a cross-sectional view in a plan view of the nozzle device according to the invention in a first operating state; FIG. 4 shows a sectional view in a side view of the nozzle device according to the invention in a second operating state, and FIG. 5 shows a cross-sectional view in a plan view of the nozzle device according to the invention in a second operating state.Exemplary EmbodimentsFigure 1 shows a cross-sectional view of a nozzle device 80 of a printhead 10 of a 3D printer 150 according to the invention. The nozzle device 80 is suitable for dispensing a liquid phase 12 of at least one printable material, wherein the nozzle device 80 has an outlet opening 8, the cross section of which can be variably adjusted for changing a volume flow of the liquid phase 12.The nozzle device 80 has two nozzle bodies 61, 62 arranged concentrically one inside the other, wherein the inner nozzle body 61 is arranged within a threaded sleeve 26 in such a way that the inner nozzle body 61 is movable relative to the outer nozzle body 62 by rotation of the threaded sleeve 26. The cross section of the outlet opening 8 of the nozzle device 80, or the nozzle cross section, is changed by the relative movement of the inner nozzle body 61 with respect to the outer nozzle body 62, in such a way that the volume flow of the liquid phase 12, or of a melt, changes. The two nozzle bodies 61, 62 arranged one inside the other thus achieve that the print head 100 can print with different volume flow depending on the setting. The melt 12 is supplied via a channel 51. The melt 12 fed in can be pressed into the die device 80 via a not-shown extruder via the channel 51.The threaded sleeve 26 can be actuated by an actuator 6 of the nozzle device 80. A transmission device 85 driven by the actuator 6 between the actuator 6 and the threaded sleeve 26 ensures a lifting and rotational movement of the inner nozzle body 61 relative to the outer nozzle body 62.The entry of liquid melt 12 upward in the direction of actuator 6 is ensured by actuator cooling 7.FIG. 2 shows a cross-sectional view in a side view of the nozzle device 80 according to the invention in a first operating state and FIG. 3 shows a cross-sectional view in a plan view.The outer nozzle body 62 has a recess 65 on its inner wall 87 and the inner nozzle body 61 has a lateral opening 63 at the level of the recess 65 of the outer nozzle body 62. In the first operating state of the print head 100 shown here, the lateral opening 63 of the inner nozzle body 61 is closed by the inner wall 87 of the outer nozzle body 62, so that the outlet opening 8 of the nozzle device 80 is formed by a nozzle opening 81 of the inner nozzle body 61. This achieves a small nozzle diameter of the nozzle device 80. The melt 12 is forced through a channel 86 arranged in the inner nozzle body 61 to the nozzle opening 81 of the inner nozzle body 61.The small cross section means a small nozzle diameter 81, or a smaller nozzle, respectively, thereby achieving high accuracy of printing.In this operating state, a seal is achieved between the two nozzle bodies 61, 62 by the outer surface or lateral surface 68 of the inner nozzle body 61 with respect to the outer nozzle body 62 in the region of the outlet opening 8.FIG. 4 shows a cross-sectional view in a side view of the nozzle device 80 according to the invention in a second operating state and FIG. 5 shows a plan view. In the operating state shown here, the outlet opening 8 of the nozzle device 80 is formed by an opening cross section 82, which results from the relative movement of the inner nozzle body 61 with respect to the outer nozzle body 62. The transmission device 85 driven by the actuator 6 between the actuator 6 and the threaded sleeve 26 provided in this operating state a lifting and rotational movement of the inner nozzle body 61 relative to the outer nozzle body 62, the inner nozzle body 61 was rotated by 180° and the simultaneous lifting movement upwards provides a gap 66 between the inner nozzle body 61 and the outer nozzle body 62, In the second operating state of the print head 100 shown here, the lateral opening 63 of the inner nozzle body 61 is aligned with the recess 65 of the outer nozzle body 62, whereby a connection is established between the opening 63 and the recess 65.The outlet opening 8 of the nozzle device 80 is thus formed by a nozzle opening 82, which is formed by the gap 66 formed between the inner nozzle body 61 and the outer nozzle body 62.Depending on the rotation and stroke of the inner nozzle body 61 by the threaded sleeve 26, a variable nozzle diameter 8 can be achieved, wherein the lateral opening 63 of the inner nozzle body 61 is either closed and sealed or kept free by the inner wall 87 of the outer nozzle body 62, depending on the position. This is controlled by the stroke and additional rotation of the inner nozzle body 61 via the threaded sleeve 26. As the inner nozzle body 61 is raised, the melt 12 exits through the nozzle opening 82 formed by the gap 66 due to the lower resistance, rather than exiting through the narrower nozzle opening 81 of the inner nozzle body 61. Before this, the melt 12 fills the recess 65 and flows around the tip of the inner nozzle body 61 and fills the gap 66 completely, so that the melt 12 can subsequently be discharged through the nozzle opening 82.In addition, the volume flow or mass flow of the melt 12 can be controlled as a result, depending on the position in which the opening 63 of the inner nozzle body 61 is in relation to the cutout 65 of the outer nozzle body 62.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 10 2021 202649 A1

[0005] DE 10 2016 213439 A1

[0006]

Claims

Nozzle device (80) for a print head (100) for a 3D printer (150), wherein the nozzle device (80) is suitable for dispensing a liquid phase (12) of at least one printable material, wherein the nozzle device (80) has an outlet opening (8), the cross section of which can be variably adjusted for changing a volume flow of the liquid phase (12), characterized in that the nozzle device (80) has two nozzle bodies (61, 62) arranged concentrically one inside the other, wherein the inner nozzle body (61) is arranged within a threaded sleeve (26) in such a way that the inner nozzle body (61) can be moved relative to the outer nozzle body (62) by rotation of the threaded sleeve (26).Nozzle device (80) according to Claim 1, characterized in that the threaded sleeve (26) can be actuated by an actuator (6) of the nozzle device (80).Nozzle device (80) according to one of the preceding claims, characterized in that the outer nozzle body (62) has a cutout (65) on its inner wall, and the inner nozzle body (61) has a lateral opening (63) at the level of the cutout (65) of the outer nozzle body (62).Nozzle device (80) according to one of the preceding claims, characterized in that, in a first operating state of the print head (100), the outlet opening (8) of the nozzle device (80) is formed by a nozzle opening (81) of the inner nozzle body (61).Nozzle device (80) according to one of the preceding claims, characterized in that, in further operating states of the print head (100), the outlet opening (8) of the nozzle device (80) is formed by an opening cross section (82) which results from the relative movement of the inner nozzle body (61) with respect to the outer nozzle body (62).A method of operating a printhead (100) having a nozzle device (80) according to any preceding claim.

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