APPARATUS FOR THE ADDITIVE MANUFACTURE OF A THREE-DIMENSIONAL WORKPIECE FROM A METAL MELT CONTAINING ALUMINUM

Abstract

The invention relates to an apparatus for the additive manufacture of a three-dimensional workpiece from a metal melt (1) containing aluminum, in particular an aluminum melt, comprising a compression chamber (2) which receives the metal melt (1) and is delimited by a piston (3) that is movable back and forth and by a nozzle body (4) having a nozzle bore (5) for discharging the metal melt (1) in drop form, wherein the nozzle body (4) has a metallophobic, in particular aluphobic structure (18), at least in the region (8) of a surface (7) adjoining the nozzle bore (5), which surface is arranged on the side facing away from the compression chamber (2),

Claims

1. An apparatus for the additive manufacture of a three-dimensional workpiece from a metal melt (1) containing aluminum, the apparatus comprising a compression space (2) which accommodates the metal melt (1) and is delimited by a piston (3) which can move back and forth and by a nozzle body (4) with a nozzle bore (5) for dispensing the metal melt (1) in the form of drops, characterized in that the nozzle body (4) has, at least in a region (8) of a surface (7) which adjoins the nozzle bore (5) and is arranged on a side remote from the compression space (2), a metallophobic structure (18).

2. The apparatus as claimed in claim 1, characterized in that the region (8) is formed from a porous structure (18).

3. The apparatus as claimed in claim 1, characterized in that the region (8) is formed from a needle-shaped structure (18).

4. The apparatus as claimed in claim 1, characterized in that the nozzle body (4) is manufactured, at least in the region of the nozzle bore (5), from a metallophilic material.

5. The apparatus as claimed in claim 1, characterized in that the nozzle body (4) takes the form of a plate.

6. The apparatus as claimed in claim 5, characterized in that the nozzle body (4) comprises a hollow cylinder (9) for radially delimiting the compression space (2).

7. The apparatus as claimed in claim 6, characterized in that the nozzle plate (12) and the hollow cylinder (9) are connected by a nozzle clamping nut (10).

8. The apparatus as claimed in claim 1, characterized in that the piston (3) is actively connected to an actuator.

9. The apparatus as claimed in claim 1, characterized in that the region (8) is formed from a stilt-shaped structure (18).

10. The apparatus as claimed in claim 1, characterized in that the nozzle body (4) has, at least in the region of the nozzle bore (5), a coating (6) with a metallophilic material.

11. The apparatus as claimed in claim 1, characterized in that the nozzle body (4) has, at least in the region of the nozzle bore (5), a coating (6) with an aluminophilic material.

12. The apparatus as claimed in claim 1, characterized in that the nozzle body (4) comprises a nozzle plate (12).

13. The apparatus as claimed in claim 1, characterized in that the nozzle body (4) is manufactured, at least in the region of the nozzle bore (5), from an aluminophilic material.

14. The apparatus as claimed in claim 1, characterized in that the piston (3) is actively connected to a magnetic or piezoelectric actuator.

15. An apparatus for the additive manufacture of a three-dimensional workpiece from a metal melt (1) containing an aluminum melt, the apparatus comprising a compression space (2) which accommodates the metal melt (1) and is delimited by a piston (3) which can move back and forth and by a nozzle body (4) with a nozzle bore (5) for dispensing the metal melt (1) in the form of drops, characterized in that the nozzle body (4) has, at least in a region (8) of a surface (7) which adjoins the nozzle bore (5) and is arranged on a side remote from the compression space (2), an aluminophobic structure (18).

16. The apparatus as claimed in claim 15, characterized in that the region (8) is formed from a porous structure (18).

17. The apparatus as claimed in claim 15, characterized in that the region (8) is formed from a needle-shaped structure (18).

18. The apparatus as claimed in claim 15, characterized in that the nozzle body (4) is manufactured, at least in the region of the nozzle bore (5), from a metallophilic material.

19. The apparatus as claimed in claim 15, characterized in that the nozzle body (4) has, at least in the region of the nozzle bore (5), a coating (6) with a metallophilic material.

20. The apparatus as claimed in claim 15, characterized in that the nozzle body (4) comprises a nozzle plate (12).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The invention is explained in detail below with the aid of the attached drawings, in which:

[0022] FIG. 1 shows a schematic longitudinal section through an apparatus according to the invention,

[0023] FIG. 2 shows a schematic drawing of a metallophobic structure,

[0024] FIG. 3 shows a first exemplary embodiment of the metallophobic structure, and

[0025] FIG. 4 shows a second exemplary embodiment of the metallophobic structure.

DETAILED DESCRIPTION

[0026] The apparatus according to the invention shown in FIG. 1 for the additive manufacture of a three-dimensional workpiece from a metal melt containing aluminum comprises a nozzle body 4 with a multi-part design which comprises a plate-shaped part and a nozzle plate 12. The nozzle plate 12 is connected, i.e. axially tensioned, to a hollow cylinder 9 by means of a nozzle clamping nut 10. A piston 3 which can move back and forth is accommodated in the cylinder 9. The piston 3, the hollow cylinder 9, and the nozzle plate 12 together delimit a compression space 2 which can be filled with a metal melt 1.

[0027] The apparatus moreover comprises an actuator (not shown) with the aid of which the piston 3 can be moved back and forth. The piston 3 is thus plunged into the compression space 2 or is retracted therefrom. In this way, pressure waves or pressure pulses are produced which press the metal melt 1 into a nozzle bore 5 of the nozzle plate 12 so that it is delivered through the nozzle bore 5 in the form of individual drops 11.

[0028] In order to ensure that the drops 11 are released in each case only at the end of the nozzle bore 5 and not at an earlier stage inside the nozzle bore 5, the nozzle plate 12 has a coating 6 of a metallophilic, in particular aluminophilic material in the region of the nozzle bore 5. The aluminophilic material improves the wettability of the surfaces adjoining the nozzle bore 5 with the metal melt 1 containing aluminum. The metal melt 1 thus has less tendency to retreat into the compression space 2 after a drop 11 has been produced such that the nozzle bore 5 remains filled with metal melt 1 and the next drop 11 can be formed immediately.

[0029] In the region 8 of a surface 7 which adjoins the nozzle bore 5 and is formed on that side of the nozzle plate 12 remote from the compression space 2, the surface 7 has a metallophobic, in particular aluminophobic structure 18. The aluminophobic structure 8 in turn assists the release of the drops 11 at the end of the nozzle bore 5, viewed in the flow direction of the metal melt 1. The surface 7 forms the nozzle plate underside 7.

[0030] In the apparatus shown in FIG. 1, the release of the drops 11 at the end is moreover promoted by the nozzle bore 5 formed in the nozzle plate 12 having sections 5.1, 5.2 with bore diameters of different sizes which are connected via a conically formed section 5.3. In this way, a nozzle bore 5 which tapers toward the end in the flow direction is created which assists the release of the drops 11 at the end.

[0031] With the aid of the apparatus shown in FIG. 1, drops 11 can thus be formed from a metal melt 1 containing aluminum which can have a defined size and be positioned precisely because they are not deflected after release and instead fall vertically downward.

[0032] FIG. 2 shows a schematic drawing of a metallophobic, in particular aluminophobic structure 18, wherein the structure 18 has a heterogenous surface texture 20 which favors the so-called lotus effect. The heterogenous surface texture 20 forms a porous structure 18 on which a drop 11 is formed.

[0033] FIG. 3 shows a first exemplary embodiment of the metallophobic, in particular aluminophobic structure 18, wherein the structure 18 has a needle- or stilt-shaped design and is arranged annularly around the nozzle bore 5. The structure 18 takes the form of a flower structure.

[0034] FIG. 4 shows a second exemplary embodiment of the metallophobic, in particular aluminophobic structure 18, wherein the structure 18 has a needle- or stilt-shaped design and is arranged in a rectangle around the nozzle bore 5. The structure 18 takes the form of a checkerboard pattern.

[0035] The structures 18 according to the invention can be formed around the nozzle bore 5 by means of vaporizing or ablating ceramic material, for example using an ultrashort pulse laser (USP laser). The objective for all the exemplary embodiments is a heterogenous surface texture 20 which favors the so-called lotus effect.

[0036] Aluminophobic structures 18 with perforations of, for example, 10-20 μm are preferred for nozzle bores 5 with a diameter of preferably 300 to 500 μm. The relative spacing between the center points of the perforations is preferably of the same size. In order to obtain the structure 18 of the second exemplary embodiment in FIG. 4, for example when two loops are made which describe lines and columns around the perforation, a perforation needs to be introduced when the sum of lines and columns is an odd number. The perforations need to be introduced in the form of a Fibonacci spiral for the structure 18 of the first exemplary embodiment in FIG. 2.

[0037] The structure 18 needs to be attached for all exemplary embodiments only in the immediate surroundings of the nozzle bore 5 because it is only there that axially symmetrical separation of the drop might be adversely affected by the drop 11 being discharged adhering to the nozzle plate underside 7. The double to triple diameter of the nozzle bore 5 provides, for example, preferred coverage of the immediate surroundings of the nozzle bore 5.