Printhead for a 3D printer and method for operating a printhead

Abstract

The invention relates to a print head (10) for a 3D printer, comprising a working volume (12) for receiving a starting material (20) whose viscosity varies, wherein the working volume (12) is formed by an internal geometry (11) of the print head (10) and has an outlet opening (13) through which a liquid phase (22) of the starting material (20) can be extruded by a piston (30) guided at least partially in the internal geometry (11) of the print head (10). According to the invention, the piston (30) comprises an outer geometry (33) which corresponds to the inner geometry (11) of the print head (10). Furthermore, the invention comprises a method for operating a print head (10), wherein the piston (30) has extruded the liquid phase (22) of the starting material (20) almost completely from the working volume (12) after a printing process and / or upon reaching an endpoint (E).

Description

[0001] The present invention relates to a printhead for a 3D printer and a method for operating a printhead. State of the art

[0002] A 3D printer for a material with variable viscosity receives a solid phase of this material as its starting material, converts it into a liquid phase, and selectively applies this liquid phase to the areas belonging to the object to be produced. Such a 3D printer includes a print head in which the starting material is prepared for printing. Furthermore, it incorporates means for generating relative movement between the print head and the build platform on which the object is to be created. This movement can be limited to either the print head alone, the build platform alone, or both.

[0003] A printhead for a 3D printer is known from WO 2018 / 086792 A1. The printhead has a feeder through which the raw material to be printed is fed into the printhead. Inside the printhead, this raw material is melted and plasticized. This molten material is then conveyed within the printhead to an exit opening, through which it is applied to a printing area.

[0004] From DE 10 2022 210 001 A1 a system for printing a three-dimensional object from a printable material is known, comprising a printing device for a 3D printer, a dosing device for filling the material to be printed and a discharge device for printing the material supplied via the dosing device.

[0005] Furthermore, it can be disadvantageous that residual melt remains in the printhead after a printing process, which can cause aging of the remaining melt, affecting subsequent printing processes.

[0006] The invention is based on the objective of providing a printhead and a method for operating a printhead that enable a stable printing process. Disclosure of the invention

[0007] Within the scope of the invention, a printhead for a 3D printer and a method for operating a printhead were developed. The printhead comprises a working volume for receiving a starting material with variable viscosity, wherein the working volume is formed by an internal geometry of the printhead and has an outlet opening through which a liquid phase of the starting material can be extruded by a piston guided at least partially within the internal geometry of the printhead.

[0008] According to the invention, the piston comprises an outer geometry that corresponds to the inner geometry of the printhead.

[0009] This ensures that the piston is guided in the printhead, or in the internal geometry of the printhead, and additionally ensures that the outer geometry of the piston, or its contour, covers the internal geometry of the printhead, or the melt channel that defines the working volume.

[0010] This advantageously ensures the removal of residual material or melt. The piston, or contour piston, pushes old, unprinted material out of the print head. This effectively prevents the melt from aging or degrading, and the print head, or extruder, can be easily cleaned, thus saving maintenance time and costs.

[0011] Furthermore, a filling and subsequent printing process can ensure that the melt is processed according to the "First in - First out" principle.

[0012] In one embodiment of the printhead, the printhead, or print extruder, can be filled through the print nozzle. A side-filling print extruder would require an additional interface.

[0013] By eliminating this interface, process safety requirements can be advantageously ensured, as additional seals and thus additional wear components or hardware components can be dispensed with.

[0014] In a further development, the internal geometry of the printhead is formed by at least a cylinder, a nozzle holder, and a print nozzle. The cylinder of the printhead serves to guide the piston, thereby advantageously achieving stable process control and piston actuation. The nozzle holder of the printhead accommodates the print nozzle and can advantageously be exchanged depending on the desired nozzle geometry.

[0015] In a further development of the invention, the piston has a first and a second piston section.

[0016] The first piston section corresponds to the internal geometry of the printhead cylinder, thus advantageously achieving stable process control and piston actuation. The second piston section corresponds to the internal geometry of the printhead nozzle carrier, thus advantageously achieving optimized emptying of the working volume.

[0017] The diameter of the second piston section, pointing towards the print nozzle, is smaller than the diameter of the first piston section, and the piston may have a conical shape at the transition between the first and second piston sections. The internal geometry of the print head is designed accordingly.

[0018] Furthermore, the invention comprises a method for operating a printhead according to the invention, wherein the piston has extruded the liquid phase of the starting material almost completely from the working volume after a printing process and / or upon reaching an endpoint. The piston, or contour piston, completely removes the molten plastic from the print extruder before each filling or refilling of the print head. This effectively prevents melt degradation due to excessively long residence times. The process control can ensure that the molten material is consumed according to the "first-in, first-out" principle. This effectively prevents any noticeable quality variations within a single component during a print job.

[0019] Further measures improving the invention are described in more detail below together with the description of preferred embodiments of the invention with reference to the figures. Examples of implementation

[0020] They show: Fig. 1 a printhead according to the invention with a piston in a first position and Fig. 2. Move the print head with the piston into a second position.

[0021] Fig. 1 and Fig. Figure 2 shows a printhead 10 according to the invention. The printhead 10, for a 3D printer (not shown), comprises a working volume 12 for receiving a starting material 20 with variable viscosity, the working volume 12 being formed by an internal geometry 11 of the printhead 10. The working volume 12 has an outlet opening 13 through which a liquid phase 22 of the starting material 20 can be extruded by a piston 30 guided at least partially within the internal geometry 11 of the printhead 10. The piston 30 comprises an outer geometry 33 that corresponds to the internal geometry 11 of the printhead 10. In this embodiment, the internal geometry 11 of the printhead 10 is formed from at least one cylinder, a nozzle carrier 16, and a print nozzle 17. The piston 30 has a first piston section 31 and a second piston section 32.

[0022] The cylinder 15 of the printhead 10 serves to guide the piston 30 and the nozzle holder 16 of the printhead 10 serves to receive the print nozzle 17. The print nozzle 17 can be screwed into the nozzle holder 16.

[0023] The first piston section 31 corresponds to the internal geometry of the cylinder 15 of the printhead 10, and the second piston section 32 of the piston 30 corresponds to the internal geometry of the nozzle carrier 16 of the printhead 10. The diameter of the second piston section 32, which points towards the print nozzle 17, is smaller than the diameter of the first piston section 31. At the transition from the first 31 to the second piston section 32, the piston 30 has a conical shape. The internal geometry 11 of the printhead 10 is designed accordingly.

[0024] In Fig. In the first position A, or starting position A, the piston 30 is located, for example, after a filling process. During the printing process, the piston 30 is moved towards the outlet opening 13 and extrudes the melt 22 from the print head 10. At the end of the printing process and / or after the print head 10 has emptied, the piston 30 reaches an endpoint E, as shown in Fig. 2 shown.

[0025] The illustrated printhead 10 enables a method for operating the printhead 10 such that the piston 30 extrudes the liquid phase 22 of the starting material 20 almost completely from the working volume 12 after a printing process and / or upon reaching the endpoint E. The piston 30, or contour piston, completely removes the melt 22, or plastic melt, from the working volume 12 before each filling or refilling of the printhead 10.

[0026] The print head 10 can be integrated into any 3D printer. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] WO 2018 / 086792 A1

[0003] DE 10 2022 210 001 A1

[0004]

Claims

[1] Print head (10) for a 3D printer, comprising a working volume (12) for receiving a starting material (20) with variable viscosity, wherein the working volume (12) is formed by an internal geometry (11) of the print head (10) and has an outlet opening (13) through which a liquid phase (22) of the starting material (20) can be extruded by a piston (30) guided at least partially in the internal geometry (11) of the print head (10), characterized by , that the piston (30) comprises an outer geometry (33) which corresponds to the inner geometry (11) of the printhead (10). [2] Printhead (10) according to claim 1, characterized by , that the internal geometry (11) of the printhead (10) is formed by at least a cylinder (15), a nozzle carrier (16) and a print nozzle (17). [3] Printhead (10) according to any of the preceding claims, characterized by , that the piston (30) has a first (31) and a second piston section (32). [4] Method for operating a printhead (10) according to any of the preceding claims, characterized by , that the piston (30) has almost completely extruded the liquid phase (22) of the starting material (20) from the working volume (12) after a printing process and / or upon reaching an endpoint (E).

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