3D PRINTING APPARATUS

Abstract

An apparatus for making three-dimensional physical objects of a predetermined shape includes a printing header having a least one arc welding torch. The arc welding torch includes an axially extending first nozzle and an axially extending non-consumable electrode, which is disposed substantially coaxially within the first nozzle and having a tip disposed at a distal end thereof and/or outside the first nozzle; means for supplying electricity to the electrode; means for supplying a protecting gas to the first nozzle for shielding the electrode from oxidising conditions; an axially extending through-hole formed through the electrode; an elongated non-electrified guide portion disposed within the through-hole terminating inwardly of the tip; and a consumable material wire that is fed through the guide portion relatively to the electrode so that the material wire is not electrified by the guide portion or by the electrode.

Claims

1. Apparatus for making three-dimensional physical objects of a predetermined shape by sequentially depositing multiple layers of solidifying material on a base member in a desired pattern, wherein the apparatus is an arc welding based three-dimensional printing apparatus, comprising a printing header for dispensing the materials to build the three-dimensional physical object, the printing header comprising: at least one arc welding torch comprising: an axially extending first nozzle and an axially extending non-consumable electrode, the electrode being disposed substantially coaxially within the first nozzle and having a tip disposed at a distal end thereof and/or outside the first nozzle; means for supplying electricity to the electrode; means for supplying a protecting gas to the first nozzle for shielding the electrode from oxidising conditions; an axially extending through-hole formed through the electrode; and an elongated non-electrified guide portion disposed within the through-hole terminating inwardly of the tip; and a consumable material wire that is fed through the guide portion relatively to the electrode so that the material wire is not electrified by the guide portion and/or by the electrode.

2. The apparatus according to claim 1, wherein the arc welding based three-dimensional printing apparatus is a gas metal arc welding (GMAW) based three-dimensional printing apparatus

3. The apparatus according to claim 1, wherein the consumable material wire is a metal wire.

4. The apparatus according to claim 1, wherein the consumable material wire is a filament material comprising conductive powder(s), conductive fiber(s), or a combination of conductive powder and conductive fibers.

5. The apparatus according to claim 1, wherein the consumable material wire comprises a filament non-metal material.

6. The apparatus according to claim 1, wherein the consumable material wire is a non-metal material having a metal surface.

7. The apparatus according to claim 1, wherein the non-consumable electrode is an arc needle electrode.

8. The apparatus according to claim 1, wherein the consumable electrode is a tungsten electrode.

9. The apparatus according to claim 1, wherein the arc welding torch comprises an axially extending element arranged between the guide portion and the first nozzle, that connects the arc welding torch with the printing header.

10. The apparatus according to claim 1, wherein the means for supplying a protecting gas to the first nozzle comprises an axially extending annular second nozzle surrounding a portion of the material wire.

11. The apparatus according to claim 10, wherein the second nozzle comprises a set of circumferential nozzle outlet openings,

12. The apparatus according to claim 11, wherein protecting gas exiting from the second nozzle through the nozzle outlet openings is guided by an inner wall of the first nozzle towards the distal end of the first nozzle.

13. The apparatus according to claim 1, wherein the guide portion comprises a conduit of electrically insulated material through which the material wire is fed relatively to the electrode.

14. The apparatus according to claim 13, wherein the conduit is coaxially disposed within the electrode.

15. The apparatus according to claim 13, wherein the material wire is fed coaxially relatively to the electrode.

16. The apparatus according to claim 8, wherein the conduit comprises ceramic.

17. The apparatus according to claim 1, further comprising two arc welding torches.

18. The apparatus according to claim 17, wherein the consumable material wire that is fed through the guide portion of the first arc welding torch is aluminium.

19. The apparatus according to claim 17, wherein the consumable material wire that is fed through the guide portion of the second arc welding torch is one of steel, plastic, and rubbery.

20. The apparatus according to claim 1, further comprising: a base member disposed in close, working proximity to the printing header; and mechanical means for moving the printing header and the base member relative to each other in three dimensions along X, Y, and Z axes in a rectangular coordinate system in a predetermined sequence and pattern and for displacing the printing header a predetermined incremental distance relative to the base member and relative to each successive layer deposited prior to the commencement of the formation of each successive layer to form multiple layers of the solidifying material, which build up on each other sequentially as they solidify after discharge from the printing header.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG. 1 shows a schematic illustration of an embodiment of an arc welding torch of a printing header of a 3D printing apparatus;

[0030] FIG. 2 shows a sectional view of the arc welding torch shown in FIG. 1;

[0031] FIG. 3 shows a sectional view of the tip of the arc welding torch during a printing process;

[0032] FIG. 4A shows a schematic perspective view of a gas metal arc welding (GMAW)-based 3D printing apparatus known from the prior art; and

[0033] FIG. 4B shows a schematic illustration of the 3D printing process using a GMAW-based 3D printing apparatus.

DETAILED DESCRIPTION

[0034] FIG. 1 shows a schematic illustration of an embodiment of an arc welding torch 1 of a gas metal arc welding (GMAW)-based three-dimensional printing apparatus.

[0035] The rest of the printing header and the other components of the GMAW-based 3D printing apparatus are not shown. These components are known from the prior art and therefore not described in detail here. By way of example, reference is made to references [1] and [2], that describe such components which could be used in combination with the arc welding torch of the present disclosure. By way of example, the 3D printing apparatus of the present disclosure may further comprise a base member 42 as shown in FIG. 4A disposed in close, working proximity to the printing header and arc welding torch. The 3D printing apparatus of the present disclosure may further comprise mechanical means as described in reference [1] for moving the printing header and the base member relative to each other in three dimensions along X, Y, and Z axes in a rectangular coordinate system in a predetermined sequence and pattern and for displacing the printing header a predetermined incremental distance relative to the base member and relative to each successive layer deposited prior to the commencement of the formation of each successive layer to form multiple layers of the solidifying material, which build up on each other sequentially as they solidify after discharge from the printing header.

[0036] The arc welding torch 1 shown in FIG. 1 is integrated in a printing header of an apparatus for making three-dimensional physical objects 48 of a predetermined shape as illustrated in FIG. 4B by sequentially depositing multiple layers 47 of solidifying material on a base member 46 in a desired pattern. The apparatus is a GMAW-based 3D printing apparatus.

[0037] The arc welding torch 1 for gas tungsten arc welding comprises an axially extending annular first nozzle 4, through which an inert shielding gas 11 such as argon or helium or mixtures thereof is fed from a supply means extending through the housing of the printing header. The nozzle 4 is disposed around a tungsten electrode 3 supplied from an electrical power source through an electrical conductor also extending through the housing of the printing header (also not shown).

[0038] The electrode 3 is disposed substantially coaxially within the first nozzle 4 and has a tip 3a disposed at a distal end 4a thereof. The electrode 3 may be pure tungsten or tungsten alloy rod. Thus, although the term tungsten is used herein, it should be understood that this term is not intended to be limited to pure tungsten, but includes all the known tungsten alloys conventionally used for GTAW electrodes.

[0039] The arc welding torch 1 further comprises an axially extending through-hole 7 formed through the electrode 3 so that the electrode 3 is hollow. The through-hole 7 may be a bore. Furthermore, an elongated non-electrified hollow guide portion disposed within the through-hole 7 is provided. The guide portion has a lower guide portion 8b disposed within the through-hole 7 terminating inwardly of the tip 3a and an upper guide portion 8a.

[0040] The arc welding torch 1 comprises an axially extending element 2 arranged between the guide portion 8 and the first nozzle 4 for connecting the arc welding torch 1 with another portion of the printing header.

[0041] A consumable metal wire 9 is fed through the guide portion 8 relatively to the electrode 3 so that the metal wire is not electrified by the metal wire guide 8b or by the electrode 3. The metal wire can be provided by a wire feed located outside of the arc welding torch 1.

[0042] Furthermore, the arc welding torch 1 comprises means for supplying a protecting gas 11 to the first nozzle 4 for shielding the electrode 3 from oxidising conditions. The means for supplying the protecting gas 11 to the first nozzle 4 comprises an axially extending annular second nozzle 6 surrounding a portion of the metal wire upstream of the tip 3a of the electrode 3. The second nozzle 6 comprises a set of circumferential nozzle outlet openings 6a, wherein protecting gas 11 exiting from the second nozzle 6 through the nozzle outlet openings 6a is guided in an substantial axial direction by an inner wall of the first nozzle 4 through a passage 5 between the first nozzle 4 and the electrode 3 towards the distal end 4a of the first nozzle 4. This is illustrated in FIG. 3.

[0043] Since the wire 9 is pre-heated by the electrode 3, more wire may be fed to the weld puddle 10. Additionally, since the lower guide portion 8b is disposed within the electrode 3, which is within the first nozzle 4, the wire 9 is always within the envelope of the shielding gas 11 so that problems resulting from oxidising of the wire are eliminated (see also FIG. 3).

[0044] As described above, the proposed 3D printing apparatus combines micro tungsten inert gas (TIG) welding with a layered manufacturing technique. A thin metal wire 9 is melted by the arc of the arc welding torch 1 and a metal bead 46 is formed. Due to the complete melting of the supplied metal wire 9, the produced parts have practical strength and the formed structures are fully dense. Additionally, it is possible to fabricate intermetallic objects by mixing two metal wires of different metal type on the forming stage and the distribution of composition can be controlled. For example, 3D objects of an aluminium-steel intermetallic alloy can be printed. Additionally, it is possible to join a metal material with a non-mental material with this approach, e.g., aluminium-plastic, aluminium-rubbery etc.

REFERENCE NUMERAL LIST

[0045] 1 Arc welding torch [0046] 2 Element connecting arc welding torch with printing header [0047] 3 Electrode [0048] 3a Tip of electrode [0049] 4 First nozzle [0050] 4a Distal end of first nozzle [0051] 5 Passage [0052] 6 Second nozzle [0053] 6a Nozzle outlet openings [0054] 7 Through-hole [0055] 8a Upper guide portion [0056] 8b Lower guide portion [0057] 9 Consumable wire [0058] 10 Weld puddle [0059] 11 Protecting gas [0060] 40 Printing header [0061] 41 Metal substrate [0062] 42 x-y stage [0063] 43 Tungsten electrode [0064] 44 Arc welding torch [0065] 45 Wire feeders [0066] 46 Metal bead [0067] 47 Layer [0068] 48 Printed 3D object [0069] 49 Consumable wire