Device and Method for Producing a Component by Means of 3D Multi-Material Printing and Component Produced Therewith

Abstract

The invention relates to a method and a device for producing a component by means of 3D multi-material pressure and to a component part produced therewith, wherein metallic and ceramic pastes, mixed with powder and binding agents, for producing the component are applied in layers by means of an extrusion process and are shaped, and the printing process is monitored by means of a monitoring device in such a way that defects in the pressure are detected by means of a camera and the defects are eliminated and/or overfilling or underfilling of each printed layer in relation to the extrusion quantity is monitored by means of a camera and/or temporary blockages in the extrusion nozzle are detected by monitoring the pressure in the region of the extrusion nozzle and released by increasing the pressure. The device comprises a corresponding monitoring device. The device can also have a mixing and feeding device with a vacuum mixing container which is connected to a vibration device. The device can comprise a ceramic construction platform having a porous structure. The component has a lattice structure with beads which are deposited at a distance from one another on a plane.

Claims

1. Method for producing a component by means of 3D multi-material printing, in particular for producing an electrical component, characterized in that by means of an extrusion process from powder and binder, mixed metallic and ceramic pastes for producing the component are applied in layers by means of an extrusion die and brought into shape, and that the printing process is monitored by means of a monitoring device in such a way that by means of a camera, defects in the print are detected, localized and compared with the measurements of a continuous monitoring system, wherein, based on detected defects, new extrusion paths are automatically created which eliminate the defects fully automatically, and/or by means of a camera, an overfilling or underfilling of each printed layer is monitored in relation to the extrusion quantity, wherein the degree of filling of each printed layer during the printing process is recorded and evaluated by means of imaging methods, and/or temporary blockages in the extrusion die can be detected by monitoring the pressure in the area of the extrusion die, wherein the blockage outside the printed body is released by increasing the pressure and the printing process is then continued.

2. Method according to claim 1 for monitoring defects in printing, characterized in that a bead deposited on the printing body during the printing process is evaluated with the aid of the camera and image recognition and evaluation methods and, in the case of defects, these are eliminated before the next layer and/or the next material.

3. Method according to claim 1 for monitoring defects, characterized in that, after completion of a material in a layer, the corresponding area is detected with the aid of the imaging materials and the course of the extrusion paths is determined by means of an image recognition method.

4. Method according to claim 1 for monitoring the overfilling/underfilling of the extrusion quantity, characterized in that the overfilling or underfilling is counteracted by means of the dynamic adaptation of a scaling factor in the form of a control loop to the printing process.

5. Method according to claim 1, in that the loosening of the blockage of the extrusion die is detected by means of the drop in the measured pressure.

6. Method according to claim 1, characterized in that a binder in the form of an emulsion of several components is used, wherein the emulsion is used for the targeted adjustment of the binder parameters.

7. Method according to claim 6, characterized in that the binder consists of polymers of different chain length, ring-shaped hydrocarbon compounds, iso-parafins, olefins, n-parafins, polysaccharides, surface-active substances or defoamers or a combination of at least two of these components.

8. Method according to claim 1, characterized in that after the component has been printed, a sintering process of the printed parts takes place, wherein the temperature level and the sintering atmosphere are selected in such a way that the binder components are expelled from the component by means of oxidation, wherein the temperature subsequently is increased to 900-1500 C., wherein the oxidized metallic components of the printed component are reduced with the aid of active gases.

9. Method according to claim 1, characterized in that by means of an automatic mixing and feeding device the metallic and ceramic paste is mixed under vacuum and fed to the print head by means of gravity and vibration.

10. Method according to claim 9, characterized in that the mixing and feeding device has an inlet opening, wherein the quantity provided for mixing is determined from the amplitude, frequency, powder consistency and diameter of the inlet opening.

11. Method according to claim 1, characterized in that by adding additives to the ceramic paste the shrinkage value during the drying and sintering process as well as the physical properties of the printing body are adjusted.

12. Device for producing a component by means of 3D multi-material printing, characterized in that mixed metallic and ceramic pastes for producing the component can be applied in layers by means of an extrusion die and brought into shape by means of an extrusion process from powder and binder, comprising a monitoring device for monitoring the printing process, wherein the monitoring device has a camera which detects and localizes defects in the print and compares them with the measurements of a continuous monitoring system, and/or has means for monitoring a print to detect temporary blockages in the area of the extrusion die and that the blockage outside the printed body can be released by increasing the pressure and the printing process can be continued, and/or has a camera monitoring the overfilling or underfilling of each printed layer in relation to the extrusion quantity, and the degree of filling of each printed layer during the printing process can be recorded and evaluated by means of an imaging method.

13. Device for producing a component by means of 3D multi-material printing, characterized in that by means of an extrusion process from powder and binder, mixed metallic and ceramic pastes for producing the component can be applied in layers by means of an extrusion die and brought into shape with a mixing and feeding device, characterized in that the mixing and feeding device comprises a mixing container under vacuum and is connected to a vibration device in such a way that the mixing container can be excited to vibrate, wherein the paste is transportable in the direction of the extrusion die by means of the vibrations.

14. Device according to claim 13, characterized in that the mixing of the ceramic and metallic pastes in the mixing vessel is carried out by means of an agitator, wherein the mixing vessel has a variable inlet opening for the supply of a powder and a supply for a binder.

15. Device for producing a component by means of 3D multi-material printing, characterized in that by means of an extrusion process of powder and binder, mixed metallic and ceramic pastes for producing the component can be applied in layers by means of an extrusion die and brought into shape, wherein the device comprises a building platform and the building platform is designed in the form of a ceramic building platform, wherein the building platform has a porous structure in such a way that moisture can be supplied to or removed from the component in a targeted manner.

16. Device according to claim 15, characterized in that the building platform has an intrinsic structure, wherein air and/or solvent can flow through said structure.

17. Device according to claim 12, characterized in that the ceramic paste preferably consists of silicate ceramics and/or that glass powder and/or technical ceramics are added to the silicate ceramics.

18. Component, produced with the method according to claim 1 and the device according to claim 12, characterized in that the component has a grid structure of beads which are deposited in a plane at a distance from one another, wherein beads are also deposited by extrusion in the plane above, wherein said beads differ in their alignment with the beads below and are at a distance from their adjacent beads in the plane.

19. Component according to claim 19, characterized in that the component is designed in the form of a heat exchanger.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The invention is explained in more detail below using an embodiment example and associated drawings, wherein:

[0052] FIG. 1 shows a mixing and feeding device according to the invention,

[0053] FIG. 2 shows a porous ceramic building platform according to the invention,

[0054] FIG. 3 shows a sectional view of a heat exchanger produced with 3D multi-material printing,

[0055] FIG. 4 shows a heat exchanger manufactured by 3D printing,

[0056] FIG. 5 shows a heat exchanger with a tube in tube arrangement.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0057] FIG. 1 shows an automatic and continuous mixing and feeding device for pastes for 3D multi-material printing. A powder 2 of metal or ceramic arranged in a storage vessel 1 is fed into a mixing vessel 3 with an agitator 4 concentrically arranged therein. The mixing container 3 has a conical shape at its lower end, which is connected to a transport hose 5 to the print head. The transport hose 5 has a flexible design and has vibration units 6 at defined intervals, which convey the ready mixed paste 7 by means of vibrations and the action of gravity in the direction of the print head.

[0058] The mixing vessel 3 has a drive motor 8 for the agitator 4 located in the mixing vessel 3. Since the mixing container is under vacuum, a connecting hose 9 is attached, which is connected to a vacuum pump. The vacuum thus generated causes continuous deaeration of the paste in mixing vessel 3.

[0059] A dosing and conveying device 10 is connected to the mixing container 3 via a further feed, which contains the binder or the individual components of the binder. The dosing and conveying device comprises a further connection for a connecting hose 11, which leads to a storage container for the binder. The dosing and conveying device 10 is connected to the mixing container 3 by means of a connecting hose 12. The binder is fed via this connection into mixing vessel 3.

[0060] The pastes are conveyed by vibration and gravity. The mixing container is preferably connected to a vibration device 14 by means of a mechanical connection 13 in such a way that it can be excited to vibrate at a variably adjustable frequency.

[0061] The vibrating movement changes the viscosity of the paste so that it can leave the mixing container 3, following gravity, downwards through the conical shape, which contains an opening, into the transport hose 5.

[0062] For 3D multi-material printing, the device has a separate mixing container 3 for mixing each paste to be printed. At least one ceramic and at least one metallic paste are mixed from powder and binder in a separate mixing vessel 3 each and fed from there via the transport hose 5 and an extruder 7.1 to the extrusion die 7.1, which is not separately designated, and thus the component is produced in one printing process.

[0063] FIG. 2 shows a schematic representation of a porous ceramic building platform, which is used in the device according to the invention. The building platform 15 has a porous intrinsic structure 16 in such a way that moisture can be added or removed from the building component in a targeted manner. This allows the curing process to be specifically influenced during the printing process. Building platform 15 has connections 17, which allow air and/or solvent to flow through the building platform 15. The air and/or solvent can be supplied or removed via connection 17.

[0064] FIGS. 3 to 5 show various forms of heat exchanger design using 3D multi-material printing.

[0065] In principle, the heat exchangers shown in FIGS. 3 to 5 are comparable to standard heat exchangers in their external form.

[0066] The heat exchanger is completely 3D printed, wherein inner structure and different materials can also be implemented by means of printing. The heat exchanger consists of a housing 18, which can be equipped with mounting devices for power electronics, for example, as required. Furthermore, the heat exchanger has at least two connections on its front side in the form of an inflow 19 and an outflow 20. Inside the housing 18 is an inner structure in the form of an inner grid structure 21 for transferring the heat from the housing 18 to the cooling fluid.

[0067] According to FIG. 3, an additional insulation layer 22 is placed between the grid structure 21 and the housing 18 of the heat exchanger, wherein the insulation layer 22 can be made of a different material. This material can be stainless steel, for example, with chemical insulation of the housing (e.g. copper) against the fluid flowing through it, or ceramic is used as electrical insulation of the fluid flowing through against the housing. The connections in the form of inflow and outflow can also have an additional insulation layer 23.

[0068] According to FIG. 4, the heating elements 25 of the heat exchanger have a ceramic insulation 24 from the inner grid structure 21. This enables, for example, the pressure of a continuous flow heater with a high power density. The heating elements 25 are arranged in such a way that they are insulated from each other and from the fluid by the ceramic insulation layer 24.

[0069] A heat exchanger with an intrinsic grid structure produced using 3D multi-material printing is shown in FIG. 5. Inside, a second fluid-carrying structure 26 is formed. The second structure 26 has a second inflow 27 and a second outflow 28, with the inflow and outflow 27, 28 serving as inlet and outlet for the inner fluid circuit. Thus, heat exchangers with high power density for hermetically separated systems, as well as several inner tubes are conceivable to increase the surface area.

[0070] FIG. 6 shows a detailed view of a grid structure 21 arranged in a housing 18, which was printed completely with housing 18.

[0071] After printing, heat treatment for hardening takes place in the form of sintering, wherein the binder is completely expelled.

[0072] The inner structure for transferring heat from the housing to the cooling fluid is fundamentally different from the known prior art.

[0073] Prior art are tube-like structures whose cross-section can also deviate from the round form.

[0074] The inner grid structure of the printed heat exchanger is created by extrusion of ceramic or metallic pastes, wherein beads are deposited in the respective plane with a defined distance between them.

[0075] Beads are also deposited by extrusion in the plane above, wherein they differ in their alignment to the beads below and have a defined distance from their neighboring beads in the plane. The angle between the alignment axes of superimposed beads can vary. The orientation of the beads alternates from layer to layer, creating a grid-like structure as shown in FIG. 6.

[0076] Since the grid and housing are made of the same material, e.g. copper, and with the same process (3D multi-material printing), a material bond is created between the grid structure, which transfers the heat to the cooling fluid and to the housing. The housing absorbs the heat from power electronics, for example. This results in a better heat transfer as there are significantly lower heat transfer resistances.

[0077] This leads to a significant increase in power density. In the case of geometric restrictions, the heat exchanger or heat sink can also be dimensioned smaller for the same power to be dissipated.

[0078] The grid structure produced by the method according to the invention can only be produced by 3D multi-material printing (extrusion printing), since from a certain degree of structural fineness, depending on the remaining opening, the remaining powder can no longer be removed in prior-art processes (powder bed processlaser melting and laser sintering).

[0079] The grid structure allows an optimum to be achieved in terms of the ratio between the surface through which heat can be exchanged and the volume through which fluid flows. At the same time, the housing can be designed to save material. Thus, grid structures with 3D multi-material printing can be produced very easily, quickly and in a material-saving manner.

[0080] A particular advantage of the printed heat exchanger is the external shape as well as the inner structure of the heat exchanger, which can be designed in practically any way. This allows integration into an environment with unfavorable space conditions.

[0081] Another advantage of using the 3D multi-material printing process is the possibility of using more than one material. The use of several materials thus results in a wide field of application.

[0082] According to the method, the housing of the grid structure, the grid structure itself and the outer housing need not be made of the same material. For example, the grid can be made of copper and the grid housing of ceramic. The outer housing can be made of stainless steel, for example.

[0083] Advantageously, the inner grid structure may contain printed ceramic insulated electrical conductors that serve as heating elements, as shown in FIG. 4. Furthermore, the inner grid structure may contain a structure that can also absorb a fluid. This structure also contains a grid structure in its interior. Such a tube in tube variant is shown in FIG. 5. A combination of the various embodiments from FIGS. 3 to 5 is also conceivable.

LIST OF REFERENCE NUMERALS

[0084] 1 Storage tank

[0085] 2 Powder

[0086] 3 Mixing container

[0087] 4 Agitator

[0088] 5 Transport hose

[0089] 6 Vibration unit

[0090] 7 Ready mixed paste

[0091] 7.1 Extruder

[0092] 8 Drive motor

[0093] 9 Connection hose

[0094] 10 Dosing and conveying device for the binder

[0095] 11 Connecting hose to the storage container for binders

[0096] 12 Connecting hose of dosing and mixing unit of the binder

[0097] 13 Mechanical connection of vibration unit and mixing container

[0098] 14 Vibration unit for mixing container

[0099] 15 Building platform

[0100] 16 Intrinsic structure

[0101] 17 Connections for solvent and/or air

[0102] 18 Housing

[0103] 19 Inflow

[0104] 20 Outflow

[0105] 21 Inner grid structure

[0106] 22 Insulation layer

[0107] 23 Insulation layer inflow/outflow

[0108] 24 Ceramic insulation layer

[0109] 25 Heating element

[0110] 26 Second grid structure

[0111] 27 Second inflow

[0112] 28 Second outflow