DE202014008106U1 - 3D printhead consisting of heating block with nozzle (English Hot End) for 3D printers that work according to the fused deposition modeling method, for melting filament material - Google Patents

Abstract

3D print head consisting of a heating block with nozzle (English: Hot End) for 3D printers that work according to the fused deposition modeling process, for melting filament material, characterized in that liquid cooling and several heating zones are controlled separately in the print head can to generate defined thermal conditions inside.

Description

3D print head consisting of heating block with nozzle (English: Hot End) for 3D printers, which work according to the fused deposition modeling process, for melting filament material

For 3D printers using the FDM (Fused Deposition Modeling) process, the starting material is in the form of a wire material with the same cross section (filament). This can be wound up on a spool or rod-shaped in the case of rigid materials. The filament is conveyed by FDM process through a heated chamber and melted there. The molten material is forced through a nozzle of defined cross section. At the same time there is a movement in the x and y direction. During this movement, the material is simultaneously deposited on a platform defined. A movement in the z-direction makes it possible to create further layers on the already deposited material. This layered structure characterizes the FDM method and enables the generation of three-dimensional objects or of solids. Another equivalent term for this process is FFF (Fused Filament Fabrication).

Previous heating blocks with nozzle (hot end) require very exact temperature conditions inside. Thus, at the nozzle end of the chamber, the temperature must be high enough to bring the filament material into the molten state. Through the nozzle, which is firmly connected or bolted to the chamber, the melt passes into the open air and is deposited on the platform. At the inlet side of the chamber, the temperatures must not be too high, because here the still solid filament is nachgeschoben. Only the feeding of filament at the chamber entrance leads to pushing out of molten material at the nozzle. If the temperature at the chamber entrance is too high, the filament softens and due to the lack of strength it can not be pushed or it expands due to the heating and thus clogs up the feed channel. 3D printing using the FDM process will also fail if the temperature at the nozzle end is too low and the material is insufficiently melted. The nozzle is then blocked by unmelted material. Especially at higher material throughputs, this is a common problem.

For the function of the printer, it is therefore necessary to comply with defined thermally different states in one and the same print head (hot end). Current systems try to realize this over a long finned fin area and / or have air cooling in the filament entrance area. However, this fails if the speeds increase drastically during printing, because then there is a shift in the thermal conditions in the interior of the print head (chamber). The result is that at higher speeds with the previous systems, the nozzle no longer promotes material. Even with the previous systems not every plastic or other materials with plastic as a carrier and filler, such. As ceramic or metallic material process, since these materials require different temperatures for melting.

Especially with changing requirements such. As different material or changes in printing speed, it is important to dynamically regulate the thermal conditions and adapt to always have the desired temperature profile inside the print head.

The protection specified in claim 1 invention is based on the problem to provide a printhead consisting of heating block with nozzle (hot end), in the interior (chamber) is present a defined and stable temperature profile. The inlet, where the filament enters the print head, must be below the melting temperature of the material and on the outlet side (nozzle) the temperature must be high enough to melt the filament.

The problem is solved with the protection claim (1) listed features.

The solution to achieve a defined thermal profile in the chamber of the print head is that the print head consists of several elements (components), all of which are firmly connected to each other e.g. B. by screwing. In the area in which the material enters the print head is a water cooling is provided, which is controlled by a temperature sensor. In the area of the material outlet are heating elements, which are also controlled by a temperature sensor. From the exit area of the material towards the inlet area there are several heating zones. These are characterized in that they have a heating element mounted in the print head and in each case a temperature sensor. Depending on requirements, the heating elements can be individually switched on or off. By controlling the cooled area and the control of the heating area, a stable temperature profile inside the print head can be achieved even with changing thermal conditions. Cooled and heated areas are also thermally separated by a component located between them. Accordingly, this component consists of a poor thermal conductivity material such. As ceramics, Kunstsoff, wood or the like.

The inlet portion of the chamber for the filament is connected via a connector either to a Bowden extruder or directly to an extruder which conveys the filament into the chamber.

About the inlet ( 1.1 ) (Inlet area) the material in ( 1 ) brought in. In ( 1 ) are cooling holes ( 1.2 ). These cooling holes are designed to allow flow for a cooling medium around the chamber interior. The cooling channel has no direct connection to the interior (chamber) of the heating block. The circulating channel is connected to hoses with connection connections to the outside (hose connection). The cooling medium is liquid, z. As water or liquids with corrosion protection, and is processed on an external system and cooled to the necessary temperature. ( 1 ) consists of a good heat conducting material. A temperature sensor ( 1.3 ) is in ( 1 ) and controls together with the external fluid cooling the temperature of ( 1 ) in the filament entry area. At the exit of ( 1 ) is direct ( 2 ), another element or component, with ( 1 ) connected. These are ( 2 ) around a poorly heat-conducting material that acts as a thermal interface between ( 1 ) and ( 3 ) acts. This separation layer is compared to ( 1 ) and ( 3 ) only very narrow. ( 1 ) 2 ) and ( 3 ) are firmly connected to each other, z. B. screwed. In ( 3 ) is located at the end of the nozzle ( 3.1 ) of defined diameter from which the molten filament material is conveyed to the outside. ( 3 ) exists like ( 1 ) also of a good heat-conducting material in order to ensure a uniform heat distribution in ( 3 ) to generate. To melt in ( 3 ) to achieve necessary high temperatures, are several individually controllable heating elements ( 3.2 ) in ( 3 ) attached. This can z. As heating cartridges, heating bands or heating jackets in any number. Several in ( 3 ) mounted temperature sensors ( 03.03 ) are used to control the temperature, more precisely the individual heating zone. The bearing direction of the heating elements z. B. the heating cartridges can be vertical or horizontal to the feed channel.

To reduce the heat losses of ( 3 ) is kept low ( 3 ) with a shell ( 4 ) Of poorly heat-conductive material coated and only the nozzle tip released.

The decisive advantage is that a defined temperature profile can be generated in the interior of the print head via cooling and heating zones at any time. Another advantage of the design is the better thermal separation of the areas through the use of multiple components and the thermal interface ( 2 ). In addition, the cooling with a fluid in ( 1 ) adjustable now. ( 3 ) can also melt over a longer distance, the material, which much higher throughputs of material are possible (high speed printing) and difficult melting materials, such. B. with fillers can now be processed.

LIST OF REFERENCE NUMBERS

1

Printhead upper part

1.1

inlet area

1.2

Cooling channels for liquid cooling

1.3

temperature sensor

2

Thermal separating layer

3

Print head lower part

3.1

jet

3.2

heating element

3.3

temperature sensor

4

external insulation

Claims (6)

3D printhead consisting of heating block with nozzle (English: Hot End) for 3D printers, the work according to the Fused Deposition Modeling method, for melting of filament material characterized in that in the printhead cooling by means of liquid and several heating zones are controlled separately can to generate defined thermal conditions in the interior. 3D printhead (heating block with nozzle) according to claim (1), characterized in that several elements - ( 1 ) 2 ) and ( 3 ) - interconnected, z. B. bolted, are and ( 2 ) represent a thermal separation layer. Heating block with nozzle according to one of the preceding claims, characterized in that ( 1 ) is equipped with a controllable, external fluid cooling, which is used to cool ( 1 ) serves. Heating block with nozzle according to one of the preceding claims, characterized in that different elements for heating of ( 3 ) can be used, for. As heating cartridges, heating tapes or heating jackets, this ( 3 ) and everything is insulated from the outside with a poorly heat-conducting material in order to keep the heat losses low. Heating block with nozzle according to one of the preceding claims, characterized in that the cooled area between 40% to 45% and the heated area also represents 40% to 45% based on the total volume (or volume). The thermal separation has 10% to 20% share of the total volume. Heating block with nozzle according to one of the preceding claims, characterized in that for ( 1 ) and ( 3 ) very good heat conducting material and For ( 2 ) a very poorly thermally conductive material is used.

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