Manufacturing apparatus comprising collocated reduction apparatus, processor and additive-manufacturing apparatus

Abstract

A method and an apparatus for manufacturing a metallic article involve providing a non-metallic feedstock, for example in the form of an oxide of a desired metal or a mixture of oxides of the components of a desired metal alloy. A manufacturing apparatus has a reduction apparatus for electrochemically reducing the feedstock to a metallic product and a processor for converting the metallic product to a metallic powder. The powder is fed into an additive-manufacturing apparatus for fabricating the metallic article from the metallic powder. At least the reduction apparatus and the processor, and preferably also the additive-manufacturing apparatus, are collocated, or located in the same container, or in the same building, or on the same site.

Claims

1. An apparatus for manufacturing a metallic article, comprising: a reduction apparatus for electrochemically reducing a feedstock to a metallic product; a processor for converting the metallic product to a metallic powder; and an additive-manufacturing apparatus for fabricating the metallic article from the metallic powder; in which the reduction apparatus, the processor and the additive manufacturing apparatus are collocated, or are located on the same site, in which the reduction apparatus comprises an electrochemical cell in which, in use, an anode and a cathode are in contact with a fused salt and the feedstock contacts the cathode and the fused salt, and an electrical power supply for applying a cathode potential to the cathode so that the feedstock is reduced to the metallic product.

2. The apparatus according to claim 1, in which the reduction apparatus, the processor and the additive-manufacturing apparatus are collocated in the same container, or portable building.

3. The apparatus according to claim 1, in which the reduction apparatus comprises a loading unit for loading the feedstock onto a cathode and a pre-heat unit for heating the feedstock and the cathode for immersion into the fused salt.

4. The apparatus according to claim 1, in which the cathode carrying the metallic product is removable from the electrochemical cell, and in which the reduction apparatus comprises a cooling unit for cooling the cathode and the metallic product before the metallic product is processed by the processor.

5. The apparatus according to claim 3, in which, after the feedstock is loaded onto the cathode in the loading unit, the cathode carrying the feedstock is moved horizontally until it is positioned beneath the anode, and the anode and the cathode are then lowered into the fused salt.

6. The apparatus according to claim 4, in which, after reduction of the feedstock to produce the metallic product, the anode and the cathode carrying the metallic product are raised out of the fused salt, before the cathode carrying the metallic product is moved horizontally into the cooling unit.

7. The apparatus according to claim 1, in which the processor comprises a comminutor for comminuting the metallic product to produce metallic particles of the metallic product, and a classifier or screening apparatus for selecting a predetermined range of sizes of the metallic particles to form the metallic powder.

8. The apparatus according to claim 7, in which the processor comprises a spheroidising apparatus for spheroidising the metallic particles to produce the metallic powder.

9. The apparatus according to claim 7, in which the processor comprises a magnetic separator for separating ferromagnetic particles from non-ferromagnetic particles in the metallic particles or the metallic powder.

10. The apparatus according to claim 1, in which the additive-manufacturing apparatus comprises a 3D printer, a selective laser melting machine, a selective laser sintering machine, or a selective electron-beam melting machine.

11. The apparatus according to claim 1, in which the additive-manufacturing apparatus comprises a spray-coating apparatus.

12. The apparatus according to claim 1, in which the metallic powder comprises titanium or a titanium-based alloy.

13. The apparatus according to claim 1, in which a portion of the metallic powder supplied to the additive-manufacturing apparatus does not form part of the metallic product, but is oxidised by the additive-manufacturing process to form oxidised metallic powder, and in which the oxidised metallic powder is supplied as the feedstock, or as a component of the feedstock, to the reduction apparatus.

14. The apparatus according to claim 1, in which the feedstock comprises a compound containing elements corresponding to the elements forming the metallic product.

15. The apparatus according to claim 1, in which the feedstock comprises a naturally-occurring ore of the elements forming the metallic product.

16. The apparatus according to claim 1, which is capable of producing between 6 kg and 12 kg of the metallic powder per day.

17. A method for manufacturing a metallic article from a powder feedstock, comprising controlling the electrochemical reduction of a predetermined feedstock to produce a metallic product, converting the metallic product to a metallic powder, and fabricating the metallic article from the metallic powder by additive manufacturing, using the apparatus according to claim 1 wherein reduction, conversion and fabrication are collocated, or located in the same container, or the same building, or are located on the same site.

18. A control method for controlling a materials-handling, or manufacturing, apparatus comprising the reduction apparatus, the processor and the additive-manufacturing apparatus of claim 1, comprising the steps of providing control parameters or expert system control from a remote server to a locally-situated controller, and operating the locally-situated controller to control the materials-handling apparatus to produce a desired metallic article.

19. The control method according to claim 18, including the step of providing feedback from the materials-handling apparatus to the locally-situated controller, and optionally to provide feedback from the locally-situated controller, for controlling the materials-handling apparatus.

20. The control method according to claim 18, comprising the step of the remote server providing control parameters or expert system control to, and optionally receiving feedback from, a plurality of locally-situated processors coupled to respective materials-handling apparatus, optionally on different sites.

21. The control method according to claim 18, in which when a particular feedstock is provided for the materials-handling apparatus, the remote server provides control parameters to the locally-situated controller to enable the locally-situated controller to control the materials-handling apparatus to process the feedstock.

22. The control method according to claim 21, comprising the steps of, when a desired metallic product is to be fabricated from a desired metal alloy, providing a corresponding feedstock for the materials-handling apparatus and providing control parameters from the remote server to the locally-situated controller to enable the locally-situated controller to control the materials-handling apparatus to fabricate the metallic article.

23. The control method according to claim 21, comprising the step of providing the feedstock in a pre-packaged quantity of feedstock, and providing from the remote server corresponding control parameters for processing the pre-packaged quantity of feedstock to fabricate the metallic article.

24. The apparatus according to claim 11, wherein the spray-coating apparatus is a plasma spray coating apparatus.

25. The apparatus according to claim 15, wherein the ore is rutile.

Description

DESCRIPTION OF SPECIFIC EMBODIMENTS AND BEST MODE OF THE INVENTION

(1) Specific embodiments of the invention will now be described by way of example, with reference to the accompanying drawings, in which:

(2) FIG. 1 is a schematic diagram of a first embodiment of the invention;

(3) FIG. 2 is a schematic diagram of a reduction apparatus of the first embodiment of the invention; and

(4) FIG. 3 is a schematic diagram of a processing apparatus of the first embodiment of the invention.

(5) A first embodiment of the invention is a highly-automated system that produces 6 to 12 kg of titanium and/or titanium alloy powder per 24 hours cycle with a reduced footprint compared to comparable conventional apparatus. The system, or unit, encompasses a reduction apparatus 2, a processor 4, and a selective laser melting apparatus 6. The reduction apparatus comprises an electrochemical cell for reducing a feedstock, which is either in the form of a powder of a metal compound, or a powder of oxidised metal (produced as a by-product of an additive manufacturing process), or a mixture of the two. The processor comprises stages for processing the metallic product of the reduction stage and product cleaning, sizing and bagging in inert atmosphere.

(6) The size and design of the unit in this embodiment is based on the material feed requirements of the selective laser melting (SLM) machine 6. Such machines have an average bed mass of 50 to 70 kg and a deposition rate between 40 and 160 g/h for a total of about 2.4 kg/day. Electron beam melting (EBM) machines typically have a somewhat smaller bed mass between 20 to 50 kg but a faster deposition rate around 500 g/h which equates to a metallic powder feed requirement of about 12 kg/day. Embodiments of the invention could be constructed to cover either of these scenarios.

(7) In operation, a feedstock is charged onto a cathode tray that is then put in a pre-heat apparatus 8. A tray transport machine 10 moves the tray from the pre-heat to the electrochemical reduction chamber 12 and when the electro-reduction cycle is over it moves the tray with reduced metallic product on it in to a cooling station 14. The reduction apparatus is then ready to accept another tray to continue the cycle. The tray will then be taken when at room temperature and enters the processor 4, where it is soaked in a bath (not shown) to remove unwanted salt from the metallic product. The resulting product, in the form of a lightly-sintered block, is then further post processed by crushing or comminuting 16, further washing and milling 18, magnetic separation to remove ferromagnetic impurities 20, drying in argon 22, sieving or classifying 24, and packing 26 for supply to the SLM apparatus. Preferably, the product is additionally plasma spheroidised (not shown) before it is packaged for supply, as spherical metallic powder, to the SLM apparatus.

(8) An object of a preferred embodiment of the invention is to provide a compact and highly-automated instrument for carrying out the following steps: place an oxide powder on a cathode tray, input the oxide powder on the tray to the apparatus, conduct electrolysis and retrieve the tray, feed the reduced metallic product to a processor which will crush the lightly-sintered block, or cake, of product, wash and dry the resulting metallic particulate, magnetically separate metallic impurities and subsequently bag the powder under argon for storage or spheroidisation, and supply to an additive manufacturing process.

(9) Such an apparatus could process any titanium alloy within a range of alloying elements as well as regenerate powder previously handled by the SLM apparatus, but which has not formed part of the metallic article produced by the SLM process.

(10) It is envisaged that fused salt, preferably a mixture of calcium chloride and calcium oxide, in the electrochemical cell will be contained in a metal crucible provided with cathodic protection to avoid corrosion, the anode will have the ability to move up and down whilst the tray will travel transversely from the pre-heat, underneath the anode, then vertically with the anode in to the bath and (following reduction) upwards and sideways in to the cooling chamber as shown in FIG. 2.

(11) The electrochemical cell is designed to the following specifications:

(12) Current Density: 5000-7500 A/m2

(13) Tray load (oxide): 6-12 kg

(14) Cycle time: 12 to 24 h

(15) Metal production: 5 to 8 kg/day

(16) Anode and cathode diameter: 40 to 60 cm

(17) Anode material: carbon

(18) Salt inventory: 200 to 400 litres

(19) Salt: mixture of CaCl.sub.2) and CaO

(20) Operative salt temperature: 950 C

(21) Heating: External, with internal heating once the cell is in operation

(22) Atmosphere: Argon in the cooling station, CO/CO.sub.2 atmosphere in the electrochemical cell and normal air in the pre-heat.

(23) The inventors have put significant effort into optimising the post-reduction processing, and in a preferred embodiment the processor will comprise the following stages: 1. Soaking 2. Cake breaking 3. Particulate comminution 4. Wet attritioning 5. Wet magnetic separation 6. Fluid bed drying 7. Product sizing 8. Product packaging

(24) A simplified vision of the internals of this unit can be seen in FIG. 3.

(25) The processor preferably also carried out spheroidisation, advantageously based on induction plasma technology to produce round powder particles. Particles are fed in to a chamber in which plasma is created, fall through the chamber and melt to then solidify again in spherical form.

(26) Utilising a spheroidising unit benefits the powder produced in the following ways: Improve powder flow Decrease powder porosity Improve product quality

(27) In addition to these considerations, the preferred embodiment of the invention comprises a programmable control system, for controlling the functionality described above. In addition, the control system is coupled, for example over the internet or other remote communication, to a remote server operated by a system operator. In this way the system operator can optimise the performance of the apparatus, and can control and optimise the performance of multiple similar apparatus, installed at different locations.