Print head for a 3D printer and 3D printer for manufacturing a component

Abstract

The invention relates to a print head (1) for a 3D printer, comprising a housing (2) with a heater (3) for providing a liquid phase of a material (4, 4.1) and a nozzle (5) for dispensing the liquid phase of the material (4, 4.2) from the print head (1). The invention is characterized in that a heating ring (10) with heating elements (11) is arranged in the area of ​​the nozzle (5). Furthermore, the invention comprises a 3D printer (100) for producing a component (20) with a print head (1) according to the invention.

Description

State of the art

[0001] 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.

[0002] The printhead has a first operating state in which liquid material is extruded, and a second operating state in which no liquid material is extruded. The second operating state is used, for example, when moving to a different position on the work surface and no material should be dispensed along the way. Switching between the two operating states of the printhead can be achieved, for example, by turning the extrusion of the solid feed material on or off.

[0003] The most common method is fused deposition modeling (FDM), in which a filament made from the starting material is melted in an electrically heated extruder nozzle and deposited layer by layer onto a platform. In the form of such a filament, the starting material is very expensive.

[0004] DE 10 2017 212 305 discloses a 3D printer comprising a build chamber for receiving a substrate carrier on which a workpiece can be built up layer by layer by a print head, wherein means for locally heating the workpiece are arranged within the build chamber. These means can be heating elements for heating the substrate carrier or radiant heaters for heating the immediate vicinity of the workpiece.

[0005] A disadvantage of these solutions is that not only the part of the workpiece to be printed, but also the entire workpiece and the surrounding area are heated, which is not always desirable.

[0006] The invention is based on the objective of providing a compact printhead for a 3D printer that enables targeted thermal control with high printhead dynamics and thus a stable printing process. Disclosure of the invention

[0007] The present invention relates to a print head for a 3D printer and a 3D printer for manufacturing a component.

[0008] The print head for a 3D printer includes a housing with a heater to provide a liquid phase of a material and a nozzle to expel the liquid phase of the material from the print head. According to the invention, a heating ring with heating elements is arranged in the area of ​​the nozzle.

[0009] A common challenge in 3D printers and 3D extruders is maintaining the correct temperature of the molten material during the printing process. A constant melting temperature is crucial for producing components with usable properties, particularly good layer adhesion. Insufficient temperature control can lead to poor adhesion between layers and consequently to inferior print results.

[0010] In the printhead according to the invention, in addition to the heating element in the housing of the printhead, heating elements or heating cartridges are arranged in the heating ring and are thus positioned close to the heat-conducting area between the nozzle and a base body of the heating ring in order to ensure efficient heat transfer.

[0011] Optimized heat conduction into the liquid phase, or melt, within the nozzle offers further advantages such as a rapid response to temperature fluctuations. The low thermal mass within the nozzle enables quick adaptation to temperature variations or programmed temperature changes.

[0012] Furthermore, a high temperature stability is achieved, whereby the heating ring allows for a small delta between the set temperature at the heating elements or heating cartridges and the desired melting temperature in the nozzle, which advantageously ensures a constant temperature even under varying pressure conditions.

[0013] Another advantage is the significant increase in the mechanical strength of the printed components. When processing commonly used materials such as polyamide 6 with 30% glass fiber, which is typically extruded at 280 degrees Celsius, the melt exit temperature in conventional printing processes can be up to 150 degrees Celsius below the desired value. The heating ring in the nozzle area maintains or even increases the temperature precisely at the desired extrusion temperature.

[0014] The additional heating ring allows for the use of a progressively increasing temperature profile. In the rear section, i.e., the housing of the print head, a material-friendly temperature can be selected to prevent chemical damage to the material, while the necessary energy for optimal welding is supplied directly at the nozzle by the heating elements of the heating ring. This results in a significant increase in the strength of the printed layers of a component.

[0015] With polyamides, especially thermally less stable materials like flame-retardant polymers, a small offset between the set temperature of the heating elements in the heating ring and the temperature of the melt in the nozzle area has proven highly advantageous. This reliably prevents the material from being chemically stressed too much, even during short downtimes caused by the build process, and thus avoids negatively impacting the printing result.

[0016] Furthermore, the measure according to the invention prevents the component being manufactured from cooling down too quickly, thereby advantageously preventing deformation of the component or, for example, fractures in the material. At the very least, the thermal influence ensures that distortion is minimized during printing of the component, resulting in the entire component exhibiting less distortion.

[0017] This is achieved primarily through local heating, which results in better adhesion between the individual layers and improved component quality. A direct improvement is reduced warping, which proves advantageous during production, especially for large components. Local heating ensures better adhesion of the printed layers, particularly during re-printing, for example, after a refill phase.

[0018] In a further development, the printhead has an air gap between the housing and the heating ring, whereby the housing has no direct contact surface with the heating ring.

[0019] The air gap between the housing and heating ring is advantageous for compensating for the temperature-related expansion of the components involved. Furthermore, it minimizes the mass of the melt that needs to be heated by the heating ring and thermally separates it from the upper part of the print head or extruder, as the air gap reduces the number of connection points between the lower and upper parts of the print head. A more precisely controlled temperature profile can also be achieved, which is made possible by the thermal separation and the low thermal mass of the heating ring and the nozzle.

[0020] In a further development, a conical contact surface is formed between the heating ring and the nozzle to transfer the heat energy of the heating elements to the liquid phase inside the nozzle.

[0021] This design ensures that the heating ring, or heating element, remains in constant contact with the nozzle. This results in an advantageously optimized heating element for the printhead, positioned directly and very close to the nozzle. This arrangement guarantees that heat is effectively transferred from the heating ring to the nozzle and ultimately to the liquid phase, or plasticized mass of the melt, via a direct connection. Furthermore, this continuous contact ensures a constant connection between the nozzle and heating ring, even during thermal expansion. This design also allows for easy nozzle changes and quick, straightforward nozzle replacement.

[0022] In a further development, the nozzle has a nozzle opening and the nozzle opening has a horizontal distance to a nozzle surface facing away from the housing of the printhead and / or a heating ring surface facing away from the housing.

[0023] The horizontal distance between the nozzle opening and the nozzle surface and / or the heating ring surface advantageously ensures a gap between the component being printed and the heating ring or heating element. This distance has proven crucial for preventing contamination and damage to the component. If the distance is too small, contaminants or deposited particles can adhere to the print head, potentially leading to damage or contamination of the component in extreme cases.

[0024] In an advantageous further development, the horizontal distance between the nozzle opening and the nozzle surface and / or the heating ring surface is between 1 and 2.5 millimeters.

[0025] A gap greater than 1 millimeter but less than 2.5 millimeters has proven optimal, as it minimizes the risk of the aforementioned problems while simultaneously ensuring effective heat transfer into the component, or rather, the last printed layer of the component. This further contributes to the production of high-quality components.

[0026] In a further development, a thermally insulating material is arranged on the nozzle surface and / or the heating ring surface, wherein the thermally insulating material is made of polyamide film or fiber composite materials.

[0027] By placing thermally insulated material on the underside of the heating ring or nozzle, component quality is improved, particularly in the production of very small parts where the print head remains in one position for extended periods, thus radiating a significant amount of heat energy into the component via the heating ring. Particularly good results were achieved by applying polyamide film or fiber composites.

[0028] These measures help to better control the temperature of the component and prevent unwanted overheating, thereby further improving the quality and precision of the manufactured components.

[0029] In a further development, the heating ring is connected to the housing of the print head by a connecting device, wherein the connecting device has at least a spring device and a collar.

[0030] The heating ring, or heating device, is designed so that it is held down by springs in the spring assembly, providing flexibility to accommodate the thermal expansion of the components. The connecting device advantageously allows for easy nozzle changes without having to disassemble the heating ring. A collar on the connecting device prevents the spring force from separating the heating ring from the print head.

[0031] Furthermore, the invention comprises a 3D printer for manufacturing a component with a print head according to the invention.

[0032] In a training course, during a printing process, the horizontal distance between the component and a nozzle surface facing the component and / or a heating ring surface facing the component is between 1 and 2.5 millimeters.

[0033] The horizontal distance between the component and the nozzle surface and / or the heating ring surface advantageously ensures a gap between the component being printed and the heating ring or heating element. This distance has proven crucial for preventing contamination and damage to the component. If the distance is too small, contaminants or deposited particles can adhere to the print head, which in extreme cases can lead to damage or contamination of the component.

[0034] A gap greater than 1 millimeter but less than 2.5 millimeters has proven optimal, as it minimizes the risk of the aforementioned problems while simultaneously ensuring effective heat transfer into the component, or rather, the last printed layer of the component. This further contributes to the production of high-quality components.

[0035] Further measures improving the invention are described in more detail below, together with a description of preferred embodiments of the invention, with reference to figures. Brief description of the drawing

[0036] They show: Fig. 1 a sectional drawing of a printhead according to the invention 1 and Fig. 2 a sectional drawing of a printhead 1 according to the invention during a printing process of a 3D printer 100. Examples of implementation

[0037] Fig. Figure 1 shows a sectional drawing of a print head 1 according to the invention for a 3D printer, comprising a housing 2 with a heater 3 for providing a liquid phase of a material 4, 4.1 and a nozzle 5 for dispensing the liquid phase of the material 4, 4.2 from the print head 1, wherein, according to the invention, a heating ring 10 with heating elements 11 is arranged in the region of the nozzle 5. The heating ring 10 has a base body 18 in which the heating elements 11 are inserted or screwed in.

[0038] The heater 3, located in the upper section of the housing 2 of the printhead 1, heats the liquid phase of the material 4, 4.1 in a melting chamber 19 to the required preheating temperature for printing. A piston (not shown) pushes the melt 4 towards the nozzle 5 during operation and expels it from the printhead 1 through a nozzle opening 15 to produce a component 20. The heating ring 10 allows for a progressively increasing temperature profile within the melt 4 from the first section 4.1 to the second section 4.2. In the first section 4.1, i.e., within the housing 2 of the printhead 1, a material-friendly temperature can be selected by the heater 3, while the energy required for an optimal printing process can be supplied directly at the nozzle 5 by the heating elements 11 of the heating ring 10.

[0039] The printhead 1 has an air gap 8 between the housing 2 and the heating ring 10, whereby the housing 2 has no direct contact surface with the heating ring 10. The air gap 8 provides thermal separation between the housing 2 of the printhead 1, heated by the heater 3, and the base body 18 of the heating ring 10. In addition to thermal insulation, the air gap 8 also allows for compensation of temperature-related expansion of the components involved. Furthermore, the amount of melt 4, 4.1 that needs to be heated by the heating ring 10 is minimized due to space constraints.

[0040] A conical contact surface 13 is formed between the heating ring 10 and the nozzle 5 for transferring the heat energy from the heating elements 11 to the liquid phase 4.2 within the nozzle 5. The heating ring 10, or heating device 10, is thus connected to the nozzle 5 in a contact-locking manner. This arrangement ensures that the heat is effectively transferred via the conical contact surface 13 from the heating ring 10 to the nozzle 5 and finally to the liquid phase 4.2, or the plasticized mass of the melt 4.2. The conical contact also ensures that a constant connection between the nozzle 5 and the heating ring 10 is maintained even during thermal expansion. The nozzle 5 is screwed into the housing 2 of the printhead 1.

[0041] The nozzle opening 15 has a horizontal distance to a nozzle surface 16 facing away from the housing 2 of the printhead 1 and / or to a heating ring surface 17 facing away from the housing 2, wherein the horizontal distance between the nozzle opening 15 and the nozzle surface 16 and / or the heating ring surface 17 is preferably between 1 and 2.5 millimeters. Furthermore, depending on the operation and the material 4 to be printed, the printhead 1 can have a thermally insulating material 30 on the nozzle surface 16 and / or the heating ring surface 17, wherein this is preferably made of polyamide film or fiber composites.

[0042] The heating ring 10 is connected to the housing 2 of the printhead 1 by a connecting device 7 and has at least one spring device 14 and a collar 12. The heating ring 10 is held down by springs 14 of the spring device 14, which provides flexibility to respond to the thermally induced expansion of the components. The connecting device 14 is designed such that the nozzle 5 can be easily changed without having to disassemble the heating ring 10. The collar 12 on the connecting device 14 prevents the spring force of the springs 14 from separating the heating ring 10 from the printhead 1.

[0043] Fig. Figure 2 shows a sectional drawing of a printhead 1 according to the invention during a printing process of a 3D printer 100. The structure of the printhead 1 is shown in Fig.1 sufficiently described, wherein here additionally a horizontal distance between the component 20 and a nozzle surface 16 facing the component 20 and / or a heating ring surface 17 facing the component 20 is shown. This distance is preferably between 1 and 2.5 millimeters. The component 20 is partially represented by two layers 21, 22 applied by the print head 1, wherein the currently printed layer 21 is applied on the previously printed layer 22 and both layers 21, 22 of the component 20 to be printed are optimally connected or welded together by the print head 1 according to the invention. 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] DE 10 2017 212 305

[0004]

Claims

[1] Print head (1) for a 3D printer, comprising a housing (2) with a heater (3) for providing a liquid phase of a material (4, 4.1) and a nozzle (5) for dispensing the liquid phase of the material (4, 4.2) from the printhead (1), characterized by , that In the area of ​​the nozzle (5) a heating ring (10) with heating elements (11) is arranged. [2] Printhead (1) according to claim 1, characterized by , that the printhead (1) has an air gap (8) between the housing (2) and the heating ring (10), wherein the housing (2) has no direct contact surface with the heating ring (10). [3] Printhead (1) according to any one of the preceding claims, characterized by , that a conical contact surface (13) is formed between the heating ring (10) and the nozzle (5) for the transfer of the heat energy of the heating elements (11) to the liquid phase (4.2) inside the nozzle (5). [4] Printhead (1) according to any one of the preceding claims, characterized by , that the nozzle (5) has a nozzle opening (15) and the nozzle opening (15) has a horizontal distance to a nozzle surface (16) facing away from the housing (2) of the printhead (1) and / or a heating ring surface (17) facing away from the housing (2). [5] Printhead (1) according to claim 4, characterized by , that the horizontal distance between the nozzle opening (15) and the nozzle surface (16) and / or the heating ring surface (17) is between 1 and 2.5 millimeters. [6] Printhead (1) according to any one of the preceding claims, characterized by , that a thermally insulating material (30) is arranged on the nozzle surface (16) and / or the heating ring surface (17). [7] Printhead (1) according to claim 6, characterized by , that the thermally insulating material (30) is made of polyamide film or fiber composites. [8] Printhead (1) according to any one of the preceding claims, characterized by, that the heating ring (10) is connected to the housing (2) of the printhead (1) by means of a connecting device (7). [9] Printhead (1) according to claim 8, characterized by that the connecting device (7) has at least a spring device (14) and a collar (12). [10] 3D printer (100) for manufacturing a component (20) with a print head (1) according to one of the preceding claims. [11] 3D printer (100) according to claim 10, characterized by , that during a printing process there is a horizontal distance between the component (20) and a nozzle surface (16) facing the component (20) and / or a heating ring surface (17) facing the component (20) of between 1 and 2.5 millimeters.

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