Device for material extrusion during additive manufacturing of three-dimensional printed objects

Abstract

The invention relates to a device (2) for material extrusion during the additive manufacturing of a three-dimensional printed object (42) using a printing device (4). In order to achieve greater strength of the printed object it is proposed that the printing device (4) is able to travel translationally in three axes (X, Y, Z) and comprises at least one nozzle (6) and at least one conveying device (8), wherein the at least one nozzle (6) is configured for extruding an extrusion material (12), wherein the at least one conveying device (8) is configured for conveying, in particular simultaneously, a filler material (16) for the extrusion material (12).

Description

TECHNICAL FIELD

[0001] The invention relates to a device for material extrusion during additive manufacturing of a three-dimensional printed object with a printing device.

[0002] Furthermore, the invention relates to a method for material extrusion during additive manufacturing of a three-dimensional printed object with a printing device.

[0003] Furthermore, the invention relates to a control unit comprising a digital logic module configured to execute such a method. BACKGROUND

[0004] Additive manufacturing of such three-dimensional printed objects is implemented, for example, by means of filament 3D printing, in accordance with shape specifications stored in a computer program or file. Common methods are, for example, "Fused Deposition Modeling" (FDM) or "Fused Filament Fabrication" (FFF), in which a material, in particular a plastic or a resin, is melted, thickened, shaped via at least one nozzle into a filament and then cooled. In particular, the melted material is applied to a base along a previously determined path. The base is either an unfinished workpiece or a support element, in particular a surface on which the workpiece is to be formed.

[0005] The material is provided in the form of a filament or a granulate, wherein the material is referred to as extrusion material. In addition to the mentioned plastics or resins, melted metals are also used as extrusion material. The plastics, in particular thermoplastics, optionally contain fillers consisting of metal or ceramic particles, wherein the metal or ceramic filled filaments are further processed after the printing process, for example by a debinding and sintering process.

[0006] In such additive manufacturing methods, the coupling between the additively manufactured layers is poorer than the strength within the printed material strand, which leads to a lower strength of the component.

[0007] The publication US 2015 / 0367576 A1 describes a method comprising providing a matrix material and a fiber material separate from the matrix material for a three-dimensional (3D) FDM printer (Fused Deposition Modeling); delivering the matrix material and the fiber material to a printing site of the FDM-3D printer while maintaining the separation of the fiber material from the matrix material up to the printing site of the FDM-3D printer, wherein the delivering comprises melting the matrix material and embedding the fiber material in the matrix material.

[0008] The publication WO 2013 / 017284 A2 describes a method for manufacturing a three-dimensional object from a solidifiable material, which in the initial state is present in fluid form or can be liquefied. To this end, the solidifiable material is introduced in the fluid phase into a material reservoir. From there, the material is discharged via a discharge opening of a discharge unit in the direction of an object carrier for the three-dimensional object to be manufactured. The object carrier or the three-dimensional object on the one hand and the discharge unit on the other hand can be moved relative to each other in space. By means of the following: namely, at least one seamless fiber element is transported to the object spaced apart from the discharge opening for the solidifiable material while the solidifiable material is being discharged, and is embedded into the discharged solidifiable material at the three-dimensional object to be manufactured, a method and an apparatus for manufacturing a three-dimensional object having improved material properties are provided in the production method. SUMMARY

[0009] It was therefore the object underlying the present invention to provide a device for material extrusion during additive manufacturing of a three-dimensional printed object by means of which a greater strength of the printed object is achieved.

[0010] According to the invention, this object is achieved by a device for material extrusion during additive manufacturing of a three-dimensional printed object by means of a printing device, wherein the printing device is translatable along three axes and comprises at least one nozzle and at least one conveying device, wherein the at least one nozzle is configured for extruding an extrusion material, wherein the at least one conveying device is configured for conveying, in particular simultaneously, a filler material for the extrusion material, wherein the filler material has fibers which are in particular profiled, wherein the fibers are processed into a fabric band, wherein the fibers of the fabric band have a connection mechanism for establishing a form-fit connection to an adjacent fabric band.

[0011] Further, according to the invention, the object is achieved by a method for material extrusion during additive manufacturing of a three-dimensional printed object by means of a printing device, wherein the printing device is translatable along three axes and comprises at least one nozzle and at least one conveying device, wherein an extrusion material is extruded by means of the at least one nozzle, wherein a filler material for the extrusion material is conveyed, in particular simultaneously, by means of the at least one conveying device, wherein the filler material has fibers which are processed into a fabric band, wherein the fibers of the fabric band have a connection mechanism, and wherein a form-fit connection to an adjacent fabric band is established by means of the connection mechanism.

[0012] Further, according to the invention, the object is achieved by a control unit having mechanisms for carrying out such a method.

[0013] The advantages and preferred design solutions specified below with respect to the device can meaningfully be transferred to the method and the control unit.

[0014] The invention is based on the consideration that the strength of a print object to be printed by means of extrusion printing is to be improved by the particularly simultaneous delivery of a filler material. To this end, a printing device is proposed which is displaceable in three axes and has at least one nozzle which is configured to extrude an extrusion material. Furthermore, the printing device has a particularly separate delivery device for delivering a filler material for the extrusion material. In particular, an actuator is used for the displacement, which has, for example, an electric motor and is actuated by a control unit.

[0015] For example, the nozzle and the delivery device are accommodated in a common print head. For example, the nozzle has a point-symmetrical, in particular circular, cross section at least in the region of the outlet. For example, a molten thermoplastic or a resin is used as extrusion material. The delivery device is configured to deliver the filler material for the extrusion material particularly simultaneously. In particular, the filler material is delivered separately. The separate delivery takes place locally outside the nozzle for the extrusion material. For example, metal chips, ceramic chips, plastic fibers, glass fibers and / or carbon fibers are used as filler material. By this particularly simultaneous delivery of the filler material, a higher mechanical strength of the print object is achieved.

[0016] The means for carrying out the method of the control unit comprise, for example, a digital logic module, in particular a microprocessor, a microcontroller, an FPGA (field-programmable gate array) or an ASIC (application-specific integrated circuit), which is configured to operate the device for material extrusion.

[0017] The filler material has fibers, in particular profiled fibers. Such fibers are, for example, plastic fibers, glass fibers and / or carbon fibers. For example, the fibers are, for example, cord-like, twisted to form fiber bundles, so that the twisted fiber bundles constitute a profiled surface, in particular a mechanically more stable connection to the extrusion material compared to a smooth surface. By such fibers, an improvement in the mechanical strength of the print object is achieved.

[0018] The fibers are processed into a fabric band. Such a fabric band not only strengthens the print object in the fiber direction, but also increases the strength between the layers.

[0019] The fibers of the fabric band have a connection means for establishing a form-fit connection to an adjacent fabric band. The connection means is, for example, embodied as a fiber protrusion with a hook shape or a mushroom shape. The form-fit connection is achieved, in particular, by hooking the hook-shaped or mushroom-shaped connection means. By such a connection, the mechanical strength of the print object, in particular between the layers, is increased.

[0020] A further embodiment proposes that the at least one delivery device is configured to at least partially press the filler material into the extrusion material, in particular molten. To this end, for example, the nozzle is implemented ahead in the printing direction, while the delivery device is implemented behind in the printing direction.

[0021] By a movement, for example periodic, of the conveying device in the direction of the extrusion of the nozzle, in particular of the still molten filament, the filler material is pressed into the extrusion material, which leads to an improved connection of the filler material with the extrusion material and thus to a higher mechanical strength of the printed object. In particular, the point in time and the direction of the movement of the conveying device are controlled by the control unit.

[0022] A further embodiment proposes that the fabric band has a cutout in the area of the band edge. The cutout is for example periodically arranged on both sides and in particular extends essentially perpendicular to the outer band contour. This cutout in the area of the band edge simplifies the laying of the fabric band, in particular on a curved trajectory.

[0023] A further embodiment proposes that the conveying device is configured for cutting the fabric band and for conveying the fabric band in segments. For example, the conveying device comprises a scissor-like cutting device, which is actuated by the control unit in order to convey the fabric band in segments. In particular, by conveying the fabric band in segments, targeted gaps are able to be simplified, for example at the intended breaking point.

[0024] A further embodiment proposes that at least one conveying device is arranged rotatably relative to at least one nozzle, such that the nozzle and the conveying device are arranged centred on the curved trajectory to be printed. In order to extrude with the nozzle and to convey the filler material with the conveying device simultaneously on the curved trajectory, at least one conveying device is arranged rotatably relative to at least one nozzle. During the printing on the curved trajectory, the angle of rotation is adjusted dynamically by rotating the conveying device, such that the nozzle and the conveying device are always arranged centred on the curved trajectory to be printed. The dynamic adjustment is controlled by the control unit. By means of this device, complex printed objects are also able to be realised quickly and inexpensively.

[0025] A further embodiment proposes that a support element is provided, on which the three- dimensional printed object to be printed can be arranged, wherein the support element is configured in such a way that it can be moved in an at least rotatable azimuthal and / or polar direction. The support element is in particular an essentially planar element, for example a glass plate, a polymer plate or a foam surface, which supports the three-dimensional printed object to be printed during the printing process. In particular, the support element is part of a printing table, which can be moved in rotation via at least one actuator, in particular comprising an electric motor. The three-dimensional printed object is for example adhesively held on the printing plate during the printing process. By means of this rotatably movable support element, it is possible to print overhangs without additional support structures. Together with a printing device which can be translated in three axes, this is referred to as five-axis printing. The rotational degrees of freedom in the azimuthal and polar directions make it possible to print complex objects quickly and at low cost. BRIEF DESCRIPTION OF DRAWINGS

[0026] In the following, the application is described and explained in more detail on the basis of embodiments shown in the drawings.

[0027] The drawings show:

[0028] Figure 1 a schematic cross-sectional view of a device for material extrusion with a printing device,

[0029] Figure 2 a schematic view of an extrusion process,

[0030] Figure 3 a schematic view of an extrusion method while printing a curved trajectory,

[0031] Figure 4 a schematic view of a connection of shape fit between fabric bands,

[0032] Figure 5 a schematic view of a three-dimensional printed object with a nominal breaking point during an extrusion method. DETAILED DESCRIPTION

[0033] The embodiments explained in the following are preferred embodiments of the application. In the embodiments, the described components of the embodiments are each a respective feature of the application, which can be considered independently of each other, which respectively improve the application independently of each other, and which can also be considered as components of the application, either individually or in different combinations from those shown. Furthermore, the described embodiments can also be supplemented by other features of the already described features of the application.

[0034] The same reference signs denote the same elements in different figures.

[0035] Figure 1 a schematic cross-sectional view of a device 2 for material extrusion with a printing device 4. The printing device 4 comprises a nozzle 6 and a delivery device 8, wherein the nozzle 6 and the delivery device 8 are accommodated in a print head 10. At least one extrusion material 12 is provided to the nozzle 6 from a reservoir via a valve device (not shown in Fig. 1, for example arranged in the print head). For example, plastic or resin is used as extrusion material. Optionally, the plastic, in particular a thermoplastic, contains a filler consisting of metal or ceramic particles, wherein the metal or ceramic filled filaments are further processed after the printing process, for example by a debinding and sintering process. For the sake of clarity, Figure 1 The reservoir and the valve device are not shown in Fig. 1. The nozzle 6 is configured such that the extrusion material 12 is extruded through an outlet 14. The printing device 4 can have a plurality of nozzles 6 (in particular arranged one after the other in a printing direction r). The delivery device 8 is configured for the delivery of a filler material 16 for the extrusion material 12, in particular simultaneously. The filler material 16 has fibers 18, for example glass fibers and / or carbon fibers.

[0036] In particular, the filling material 16 is configured as a fabric band 20 composed of glass fibers and / or carbon fibers. The fabric band 20 is applied, for example, on a carrier film 22 in the conveying device 8, wherein the fabric band 20 applied on the carrier film 22 is exemplarily wound on a rotatably supported roll 23. During the printing process, the fabric band 20 is conveyed by unwinding from the roll 23 and is separated from the carrier film 22 in the region of a guide roll 24. The fabric band 20 can be pressed, for example, at least partially into the still molten extrusion material 12 of the nozzle 6 along the extrusion direction e by moving the conveying device 8. In particular, the conveying device 8 has a cutting device 26 configured for cutting the fabric band 20 separated from the carrier film 22. The fabric band 20 can be conveyed in segments, in particular by cutting.

[0037] The print head 10 together with the nozzle 6 and the conveying device 8 is referred to as an extruder 28 and can be translated along three axes X, Y, Z by means of actuators 30, 32. For example, the extruder 28 is moved along the X and Y axes by means of an X / Y actuator 30, in particular simultaneously, while a Z actuator 32 moves the extruder 28 along the Z axis, for example in order to adjust the distance d of the nozzle 6 and / or the conveying device 8 from a substrate. The substrate is either a partially completed extruded three-dimensional printed object or a support element 34 comprising a surface 34a on which a three-dimensional printed object can be extruded. The support element 34, for example a part of a print table, can be moved in an azimuth angle Θ and an elevation angle In order to realize extruded overhangs, for example, without additional support structures.

[0038] A control unit 36 is operatively connected with the actuators 30, 32 and the extruder 28. In particular, the operation of the nozzle 6 and the conveying device 8 is controlled by the control unit 36. The control unit 36 comprises a digital logic module, for example a microprocessor, a microcontroller, an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit), which is configured for operating the device 2 for material extrusion.

[0039] The conveying device 8 is embodied in a rotatable manner with a rotatable angle a relative to the nozzle 6, such that the nozzle 6 and the conveying device 8 are respectively arranged concentrically on the curved trajectory to be printed. In particular, the absolute value of the spacing a is constant independently of the rotatable angle a. A further actuator 38 arranged in the print head 10 and comprising, for example, an electric motor, is driven by the control unit 36 in order to dynamically adjust the rotatable angle a during the extrusion process, such that the nozzle 6 and the conveying device 8 are respectively always arranged concentrically on the curved trajectory to be printed.

[0040] Figure 2A schematic diagram of the extrusion method is shown, wherein the extrusion process is shown at different points in time tl, t2. The nozzles 6 are implemented ahead in the printing direction r, while the transport device 8 is implemented behind in the printing direction r. The nozzles 6 and the transport device 8 of the printing apparatus 4 work simultaneously, wherein the nozzles 6 extrude filaments 40 from the extrusion material 12, while the transport device 8 simultaneously transports the filler material 16 implemented as a fabric band 20. In particular, the transport device 8 presses the filler material 16 at least partially into the filaments 40, which are in particular still molten. In this way, the three-dimensional printed object 42 is constructed from a plurality of filaments 40 and fabric bands 20 arranged above one another. The embedded fabric bands 20 not only reinforce the three-dimensional printed object 42 in the fiber direction, but also increase the strength between the layers.

[0041] In order to be able to plan the storage of the fabric bands 20, the functions required for this are provided in a CAM system (computer-aided manufacturing system). Here, for example, bands with different band thicknesses and / or material properties, such as elasticity, hardness, etc., can be selected. Furthermore, a storage strategy for the fabric bands 20 can be determined in the CAM system. By means of this storage strategy, for example, it is determined at which location the fabric bands 20 are transported. Figure 2 A further embodiment of the apparatus 2 for material extrusion corresponds to the embodiment in Figure 1 .

[0042] Figure 3 A schematic diagram of the extrusion method is shown when printing a curved trajectory 44. The nozzles 6 of the printing apparatus 4 are implemented ahead in the printing direction r, while the transport device 8 is implemented behind in the printing direction r. The transport device 8 is implemented with a rotatable rotation angle a relative to the nozzles 6, so that the nozzles 6 and the transport device 8 are always arranged centered on the curved trajectory 44 to be printed. The fabric band 20 has a cutout 46 in the region of the band edges in order to simplify the laying of the fabric band 20 on the curved web 44. Furthermore, the fibers 18 can have a profiling 48, which for example comprises protrusions and / or recesses, in order to improve the connection to the extrusion material 12. Figure 3 A further embodiment of the extrusion method corresponds to the embodiment in Figure 2 .

[0043] Figure 4 A schematic diagram of the form-fit connection between the fabric bands 20 is shown. The fibers 18 of the fabric band 20 comprise a connection mechanism 50 for establishing a form-fit connection to an adjacent fabric band 20. The connection mechanism 50 is for example configured as a fiber protrusion with a hook shape or a mushroom shape. The form-fit connection is in particular achieved by hooking the hook-shaped or mushroom-shaped connection mechanism.

[0044] Figure 5A schematic view of a three-dimensional printed object 42 with a nominal breaking point 52 during an extrusion process is shown. The textile tape 20 is left empty in the area of the nominal breaking point 52 in order to facilitate the separation at the nominal breaking point 52. Figure 5 Another embodiment of the extrusion process in Figure 3 corresponds to the embodiment in

[0045] In summary, the present application relates to a device 2 for extruding material during the additive manufacturing of a three-dimensional printed object 42 with a printing device 4. In order to achieve greater strength of the printed object it is proposed that the printing device 4 is able to travel translationally in three axes X, Y, Z and comprises at least one nozzle 6 and at least one conveying device 8, wherein the at least one nozzle 6 is configured for extruding 12 an extrusion material, wherein the at least one conveying device 8 is configured for conveying (in particular simultaneously) a filler material 16 for the extrusion material 12.

Claims

1. A device (2) for material extrusion during additive manufacturing of a three-dimensional printed object (42) using a printing device (4), characterized in that the printing device (4) is translatable in three axes (X, Y, Z) and comprises at least one nozzle (6) and at least one conveying device (8), wherein at least one of the nozzles (6) is configured for extruding an extrusion material (12), wherein at least one of the conveying devices (8) is configured for conveying a filler material (16) for the extrusion material (12), wherein the filler material (16) has fibers (18), wherein the fibers (18) are processed into a fabric band (20), wherein the fibers (18) of the fabric band (20) have a connection mechanism (50) for establishing a form-fit connection to an adjacent fabric band (20).

2. The device (2) according to claim 1, characterized in that At least one of the conveying devices (8) is configured for at least partially pressing the filler material (16) into the extrusion material (12).

3. The device (2) according to claim 1 or 2, characterized in that The fabric band (20) has a cutout (46) in the area of a band edge.

4. The device (2) according to claim 1 or 2, characterized in that The conveying device (8) is configured for cutting and for conveying the fabric band (20) in segments.

5. The device (2) according to claim 1 or 2, characterized in that At least one conveying device (8) is arranged rotatable relative to at least one nozzle (6) such that the nozzle (6) and the conveying device (8) are arranged centered on a curved trajectory (44) to be printed.

6. The device (2) according to claim 1 or 2, characterized in that There is a support element (34) on which the three-dimensional printed object (42) to be printed can be arranged, wherein the support element (34) is configured to be rotatable at least in an azimuth angle (θ) and / or an elevation angle (φ).

7. The apparatus (2) according to claim 1, characterized in that At least one of the conveying devices (8) is configured for simultaneously conveying a filler material (16) for the extrusion material (12).

8. The apparatus (2) according to claim 1, characterized in that The fibers (18) have a profile configuration.

9. The device (2) according to claim 2, characterized in that At least one of the conveying devices (8) is configured for at least partially pressing the filler material (16) into the molten extrusion material (12).

10. A method for material extrusion during additive manufacturing of a three-dimensional printed object (42) using a printing device (4), characterized in that the printing device (4) is translatable in three axes (X, Y, Z) and comprises at least one nozzle (6) and at least one conveying device (8), wherein an extrusion material (12) is extruded using at least one of the nozzles (6), wherein a filler material (16) for the extrusion material (12) is conveyed using at least one of the conveying devices (8), wherein the filler material (16) has fibers (18) for processing into a fabric band (20), wherein the fibers (18) of the fabric band (20) have a connection mechanism (50), and wherein a form-fit connection to an adjacent fabric band (20) is established by the connection mechanism (50).

11. The method of claim 10, wherein, The filler material (16) is at least partially pressed into the extrusion material (12) via the at least one conveying device (8). The fabric band (20) has a cutout (46) in the area of a band edge. The conveying device (8) is configured for cutting and for conveying the fabric band (20) in segments. At least one conveying device (8) is arranged rotatable relative to at least one nozzle (6) such that the nozzle (6) and the conveying device (8) are arranged centered on a curved trajectory (44) to be printed. There is a support element (34) on which the three-dimensional printed object (42) to be printed can be arranged, wherein the support element (34) is configured to be rotatable at least in an azimuth angle (θ) and / or an elevation angle (φ). At least one of the conveying devices (8) is configured for simultaneously conveying a filler material (16) for the extrusion material (12). The fibers (18) have a profile configuration. At least one of the conveying devices (8) is configured for at least partially pressing the filler material (16) into the molten extrusion material (12).

12. The method according to claim 10 or 11, characterized in that, The filler material (16) has fibers (18) for processing into a fabric band (20), and wherein the fabric band (20) is delivered in segments.

13. The method of claim 10 or 11, wherein, At least one delivery device (8) is rotated relative to at least one nozzle (6) such that the nozzle (6) and the delivery device (8) are each arranged centrically on a curved trajectory (44) to be printed.

14. The method of claim 10 or 11, wherein, A three-dimensional printed object (42) to be printed is arranged on a support element (34), wherein the support element (34) is rotated at least in an azimuth angle Θ and an elevation angle φ.

15. The method of claim 10, wherein, The filler material (16) for the extrusion material (12) is delivered simultaneously with at least one delivery device (8).

16. The method of claim 11, wherein, The filler material (16) is pressed at least partially into the molten extrusion material (12) via at least one delivery device (8).

17. The method of claim 12, wherein, The fabric band (20) is delivered in segments by cutting.

18. A control unit (36) comprising a digital logic module, characterized in that, The digital logic module is configured to perform the method according to any one of claims 10 to 17.

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