Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
  • B29C64/20—Apparatus for additive manufacturing; Details thereof or accessories therefor
  • B29C64/205—Means for applying layers
  • B29C64/209—Heads; Nozzles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
  • B29C64/10—Processes of additive manufacturing
  • B29C64/106—Processes of additive manufacturing using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
  • B29C64/30—Auxiliary operations or equipment
  • B29C64/307—Handling of material to be used in additive manufacturing
  • B29C64/321—Feeding
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y10/00—Processes of additive manufacturing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y30/00—Apparatus for additive manufacturing; Details thereof or accessories therefor
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y70/00—Materials specially adapted for additive manufacturing

Definitions

• the present invention relates to a print head for 3D printers for the selective local output of the liquid phase of the starting material.
• a 3D printer for a material with variable viscosity receives a solid phase of this material as a starting material, creates a liquid phase from it and applies this liquid phase selectively to the points that belong to the object to be created.
• Such a 3D printer includes a print head in which the raw material is prepared for printing. Means are also provided for generating a relative movement between the print head and the work surface on which the object is to be created. Either only the print head, only the work surface or both the print head and the work surface can be moved.
• the printhead has a first operating state in which liquid material emerges from it and a second operating state in which no liquid material emerges 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 deposited on the way there. It is possible, for example, to switch between the two operating states of the print head by switching the propulsion of the solid starting material on or off.
• DE 10 2016222 306 A1 discloses a print head for a 3D printer which receives a granular starting material and conveys it with a piston into the zone in which the starting material is plasticized.
• a print head for a 3D printer comprises a feed for a starting material of variable viscosity as well as a nozzle which tapers in the direction of flow of a liquid phase of the starting material for dispensing this liquid phase through an outlet opening.
• the starting material can in particular be converted into the liquid phase, for example, by a heater attached to the print head. Even if this phase is physically liquid, it is typically still so viscous that it does not pass through the outlet opening of the nozzle of its own accord.
• At least one pressure generator is therefore provided in order to raise the pressure of at least part of the liquid phase to a base pressure.
• at least one pressure modulator connected between the pressure generator and the nozzle is provided in order to model the pressure of at least part of the liquid phase around the base pressure.
• the pressure generator can, for example, be a solid operating medium that acts on the liquid phase of the starting material, such as a piston.
• the pressure generator can, however, also comprise, for example, a feed for compressed air or another gaseous pressure medium.
• the still solid end of this filament can act like a piston on the liquid phase of the starting material and in this respect also serve as a pressure generator.
• the shear viscosity is a viscosity that is caused by the shear of the starting material.
• the flow rate increases sharply, so that a shear occurs.
• the shear introduces energy into the starting material and increases its temperature, which in turn affects the viscosity. This change in viscosity can be at least partially compensated for by modulating the pressure.
• an actuator can be used for the pressure generator which is specially designed to be moved at a medium speed and constantly and thereby to exert a high overall force.
• the pressure modulator on the other hand, it is possible, for example, to use an actuator which is specially designed for fast dynamic movements and is only able to exert a lower total force for this. The advantages of both types of actuators can thus be combined with one another.
• the volume of liquid starting material on which the pressure modulator acts can be kept significantly smaller than the volume of liquid starting material on which the pressure generator acts. It was recognized that the delay between the application of pressure with the pressure generator or with the pressure modulator, on the one hand, and the change in pressure at the outlet opening of the nozzle, on the other hand, depends on the distance that the force introduced into the liquid phase of the starting material travels within this liquid phase got to. The shorter this distance, the lower the delay. The path is coupled to the melt volume between the pressure modulator and the outlet opening. The melt volume can therefore be expressed by the distance and vice versa.
• the division of labor between the pressure generator and the pressure modulator ensures that a volume on which the pressure modulator acts, which is reduced for the purpose of a rapid response, does not excessively impair the overall material throughput that can be achieved.
• the volume on which the pressure generator acts can also be provided at the same time to convert a larger amount of solid starting material into the liquid phase with a heater.
• the pressure modulator can then "use" itself again and again from this volume.
• the pressure modulator therefore acts on a partial volume of the liquid phase which has a volume of at most 1 cm 3 and / or which fills a distance of at most 5 cm between the initiation of the pressure modulation and the outlet opening.
• the distance is linked to the volume, it works independently in conjunction with the diameter of the area in which the liquid phase of the starting material is located, for example via the shear viscosity.
• pressure modulator implies that the pressure of the liquid phase does not always have to be increased above the base pressure, but can also be decreased below the base pressure. This brings additional freedom for the choice of the operating point of the pressure generator. For example, this operating point can be selected so that at this pressure a medium flow of starting material emerges from the outlet opening. The pressure modulator can then increase or also decrease this mass flow. For this purpose, the pressure modulator can, for example, increase the volume that is available for the liquid starting material enclosed between the pressure modulator and the outlet opening.
• the pressure modulator is designed to reduce the pressure of the liquid phase at the exit opening to such an extent that the exit of the liquid phase from the exit opening is prevented.
• it is often necessary to interrupt the printing at a certain point and to continue it again after a relative movement between the print head and the object to be produced. Interrupting the exit of starting material from the outlet opening with the pressure modulator is gentler on the starting material than closing the outlet opening with a valve.
• this valve increases the flow rate of the liquid phase until the completely closed state is reached.
• the starting material is exposed to shear forces, which introduce a large amount of energy into the starting material and thus heat it up. Because of this warming the starting material can be damaged.
• the shear forces can also damage the starting material directly mechanically, for example by tearing open polymer chains. The raw material changed by these effects is weakened and literally no longer delivers what it promises. In particular, the viscosity is reduced, which in turn increases the damage effects described.
• the pressure modulator comprises a cylindrical needle which is movably mounted in a modulator channel leading to the nozzle and has a tip that tapers towards the nozzle. The position of the needle within the modulator channel then determines the volume that is available for the liquid starting material enclosed between the needle and the outlet opening, and thus also about the pressure acting on this starting material.
• the spatial arrangement of the pressure generator and its connection to the pressure modulator can in particular be designed so that there are positions of the needle in which the needle closes the connection between the pressure modulator and the pressure generator and at the same time encloses liquid starting material between its tip and the outlet opening of the nozzle .
• the starting material enclosed in this way is only affected by a change in pressure due to displacement of the needle, while this starting material is at the same time withdrawn from any influence by the pressure generator.
• a motor with a spindle drive has a particularly good price-performance ratio.
• a stack of piezoelectric elements has particularly fast dynamics.
• a hydraulic cylinder can exert maximum force.
• the drive can also be translated by any means, such as a lever, a slide or a gear. In this way, for example, the forces on the needle can be increased, or a more dynamic pressure modulation can be achieved with a slower actuator.
• the tip is dimensioned such that it can be at least partially introduced into the nozzle. If the tip penetrates particularly far in the direction of the outlet opening in this way, the volume enclosed between the tip and the outlet opening can be particularly small. As previously explained, this minimizes the delay.
• the tip is dimensioned in such a way that it can at least partially pass through the outlet opening. In this way, the tip can close the outlet opening, for example, during pauses in printing or, for example, also clean it if solidified starting material and other solids have settled there. This increases the efficiency of the 3D printer.
• the pressure generator comprises a cylindrical piston which is movably mounted in a main channel that can be filled with the liquid phase.
• This main channel can then also be used, for example, to melt solid starting material into the liquid phase. If this main channel is heated, for example, solid starting material added in granulate form can be plasticized by the combination of heat from the heating and pressure from the piston.
• the ratio of the diameter of the needle outside the area of the tip to the diameter of the piston is 1: 3 or smaller, preferably 1: 4 or smaller.
• the associated needle can then also be manufactured particularly easily and inexpensively with the required strength.
• the pressure generator and the pressure modulator act within a heatable build-up chamber for the object to be produced on the liquid phase of the starting material and are mechanically coupled to at least one drive source arranged outside the build-up chamber.
• Most inexpensive power sources are designed to operate at a temperature of 60 ° C or less.
• the liquid starting material discharged from the outlet opening and deposited on the object to be produced does not cool down immediately to room temperature, but rather the produced object is cooled as a whole first. This improves the adhesion of the printed layers of the object to one another, and thus also the mechanical stability of the object as a whole.
• the object is mechanically less distorted and therefore corresponds more precisely to its specification. This is particularly advantageous when the object is to be brought into a mechanical fit or some other mechanical engagement with other components, for example.
• temperatures in the range between 60 ° C and 100 ° C are set in the build-up chamber.
• At least part of the area in which the pressure generator is able to increase the pressure of the starting material has a heater for generating a liquid phase of the starting material.
• the drive source for the pressure modulator is thermally isolated from this heater.
• the heated area of the pressure generator can be thermally encapsulated.
• the drive source for the pressure modulator can also be thermally encapsulated and optionally also cooled, for example.
• FIG. 1 embodiment of a 3D printer 1 with a build-up chamber 16 for the object 3 to be produced
• FIG. 2 exemplary embodiment of a 3D printer 1 with insulation 18 between heated pressure generator 12 and actuator 13 * of pressure modulator 13
• Figure 1 shows an embodiment of a 3D printer 1 with the print head 10.
• the 3D printer 1 has a heatable build-up chamber 16 for the object 3 to be produced on a build-up surface 19.
• the print head 10 comprises components arranged both inside and outside the build-up chamber 16.
• the print head 10 comprises a feed 11 for the starting material 20, which in this exemplary embodiment is fed in a granular solid phase 21.
• a pressure generator 12 provided with a heater 17, the solid phase 21 of the starting material 20 is plasticized to form a liquid phase 22.
• the pressure generator 12 comprises a main channel 12a, in which a piston 12b is guided, and a drive source 12 * for the piston 12b.
• the main channel 12a and the piston 12b are guided through the insulation of the installation space 16 to the drive source 12 * arranged outside the installation space 16.
• the pressure generator 12 raises the pressure of the liquid phase 22 of the starting material 20 to a base pressure.
• the print head has a nozzle 14 with an outlet opening 15 through which the liquid phase 22 is able to exit the print head in the direction of the object 3 to be produced.
• the pressure of the liquid phase 22 is modulated by the pressure modulator 13 connected between the pressure generator 12 and the nozzle 14.
• This pressure modulator 13 comprises a modulator channel 13a in which a needle 13b with a tip 13c tapering towards the nozzle 14 is guided.
• the needle 13b can in particular enclose a portion of the liquid phase 22 between itself and the outlet opening 15. As indicated in FIG. 1, this portion can in particular be withdrawn from further influencing by the pressure from the pressure generator 12.
• the pressure modulator 13 can thus increase the pressure of the said portion, but also lower it, for example in order to temporarily interrupt the dispensing of liquid starting material 22. This can In particular, for example, it is avoided that, during lateral movement movements between the print head 10 and the object 3 to be produced, threads are drawn from the liquid starting material 22 undesirably emerging from the outlet opening 15.
• the channel 13a and the needle 13b are guided through the insulation of the installation space 16 to the drive source 13 * arranged outside the installation space 16. Beyond this insulation, the temperature of the needle 13b drops rapidly. So should part of the liquid phase 22 of the starting material 20 through an imprecise fit in a space between the needle 13b and the
• FIG. 2 shows a further exemplary embodiment of a 3D printer 1 with the print head 10.
• the installation plate 19 for the object 3 to be produced is at room temperature.
• the portion of the pressure generator 12 that can be filled with the liquid phase 22 of the starting material 20 can be heated with a heater 17.
• the drive source 13 * of the pressure modulator 13 is now protected from the heat emitted by the heater 17 by thermal insulation 18.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Physics & Mathematics (AREA)
• Mechanical Engineering (AREA)
• Optics & Photonics (AREA)
• Application Of Or Painting With Fluid Materials (AREA)

Priority Applications (6)

Applications Claiming Priority (2)

Publications (1)

Family

ID=73449019

Family Applications (1)

Country Status (8)

Citations (6)

Family Cites Families (5)

• 2019
  • 2019-11-11 DE DE102019217358.6A patent/DE102019217358A1/de active Pending
• 2020
  • 2020-11-11 KR KR1020227019237A patent/KR102932211B1/ko active Active
  • 2020-11-11 IL IL302324A patent/IL302324A/en unknown
  • 2020-11-11 US US17/775,916 patent/US20230040782A1/en active Pending
  • 2020-11-11 WO PCT/EP2020/081724 patent/WO2021094355A1/de not_active Ceased
  • 2020-11-11 JP JP2022526420A patent/JP7329689B2/ja active Active
  • 2020-11-11 CN CN202080092679.5A patent/CN114981069A/zh active Pending
  • 2020-11-11 EP EP20807306.4A patent/EP4058267A1/de active Pending

Patent Citations (6)

Non-Patent Citations (1)

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