Manufacturing of a metal component or a metal matrix composite component involving contactless induction of high-frequency vibrations

Abstract

The present invention relates to a system for contactless induction of high-frequency vibrations in a volume of molten metal during the manufacturing of a metal component or a metal matrix composite component. The system includes a moveably arranged electromagnetic primary coil, adjustment means for adjusting the position of the primary coil, and a control unit for controlling the position of the primary coil to a predefined distance above, but not in contact with, an upper free surface of the molten metal. The molten metal may be contained in a foundry crucible during manufacturing. The system can be used as an additive manufacturing system, with the primary coil arranged above the melt pool. A secondary low-frequency electromagnetic coil may be arranged around and at a distance from the molten metal to induce flow and/or vibrations in the molten metal.

Claims

1. Method of manufacturing a metal matrix composite component that includes a non-metal by use of a system for contactless induction of high-frequency vibrations in a volume of molten metal during the manufacturing of a metal matrix composite component, the system including a moveably arranged electromagnetic primary coil, an adjustment means for adjusting the position of the primary coil, and a control unit for controlling the position of the primary coil to a predefined distance above and not in physical contact with an upper free surface of the molten metal during use of the system, the method comprising: providing a foundry crucible containing at least a molten metal of which the component is to be at least partly composed, arranging the electromagnetic primary coil movably above the molten metal, adjusting the vertical position of the primary coil to a predefined distance above and not in physical contact with an upper free surface of the molten metal, applying power to the primary coil so that an electromagnetic field is obtained, adjusting the vertical position of the primary coil to maintain the predefined distance, maintaining the electromagnetic field for a predefined period of time so that a desired microstructure is obtained in the component being manufactured, arranging a secondary low-frequency electromagnetic coil around an outer circumference of the foundry crucible containing the molten metal, and applying power to the secondary coil so that flow and/or vibrations are induced in the molten metal.

2. Method according to claim 1, further comprising: adding material to the molten metal in the foundry crucible and adjusting the vertical position of the primary coil accordingly.

3. Method according to claim 2, where in the material is added through a feed device being arranged so that it is surrounded by windings of the primary coil.

4. Method according to claim 1, wherein the secondary coil is used to induce vibrations of approximately 50 Hz.

5. Method for manufacturing a metal component by additive manufacturing, the method comprising: providing a work surface on which the component is to be manufactured, providing at least one deposition material from which the component is to be composed, advancing the deposition material to a localized deposition area where it is added to the component being manufactured, providing heat to the deposition area so that a free-standing melt-pool at least comprising molten metal is provided, so that the deposition material is deposited for building up the component, arranging an electromagnetic primary coil movably above the molten metal, adjusting a vertical position of a primary coil to a predefined distance above and not in physical contact with an upper free surface of the molten metal, applying power to the primary coil so that an electromagnetic field is obtained, adjusting the vertical position of the primary coil to maintain the predefined distance, and maintaining the electromagnetic field for a predefined period of time so that a desired microstructure is obtained in the component being manufactured, and mutually moving the work surface and the deposition material in a way that results in the additive manufacturing of the component.

6. Method according to claim 1, wherein the metal is selected from the group consisting of aluminium, magnesium, titanium, zirconium, beryllium, steel, copper, nickel and cobalt.

7. Method according to claim 1, wherein the method produces a metal matrix composite comprising reinforcement made from one or more of the following: SiC, ZrO2, Y2O3, Al2O3, MgO, and AlN.

8. Method according to claim 7, wherein a characteristic size of the reinforcement is 10-1000 nm.

9. Method of manufacturing a metal matrix composite component that includes a non-metal by use of a system for contactless induction of high-frequency vibrations in a volume of molten metal during the manufacturing of a metal matrix composite component, the system including a moveably arranged electromagnetic primary coil, an adjustment means for adjusting the position of the primary coil, and a control unit for controlling the position of the primary coil to a predefined distance above and not in physical contact with an upper free surface of the molten metal during use of the system, the method comprising: providing a foundry crucible containing at least a molten metal of which the component is to be at least partly composed, arranging the electromagnetic primary coil movably above the molten metal, adjusting the vertical position of the primary coil to a predefined distance above and not in physical contact with an upper free surface of the molten metal, applying power to the primary coil so that an electromagnetic field is obtained, adjusting the vertical position of the primary coil to maintain the predefined distance, maintaining the electromagnetic field for a predefined period of time so that a desired microstructure is obtained in the component being manufactured, and adding material to the molten metal in the foundry crucible and adjusting the vertical position of the primary coil accordingly, wherein the material is added through a feed device being arranged so that it is surrounded by windings of the primary coil.

10. The method of claim 9, further comprising: arranging a secondary low-frequency electromagnetic coil around an outer circumference of the foundry crucible containing the molten metal, and applying power to the secondary coil so that flow and/or vibrations are induced in the molten metal.

11. Method according to claim 9, wherein the secondary coil is used to induce vibrations of approximately 50 Hz.

12. Method according to claim 9, wherein the metal is selected from the group consisting of aluminium, magnesium, titanium, zirconium, beryllium, steel, copper, nickel and cobalt.

13. Method according to claim 9, the method being used to manufacture a metal matrix composite comprising reinforcement made from one or more of the following: SiC, ZrO2, Y2O3, Al2O3, MgO, and AlN.

14. Method according to claim 9, wherein a characteristic size of the reinforcement is 10-1000 nm.

15. Method according to claim 1, wherein the metal matrix composite comprises a metal and a non-metal.

16. Method according to claim 9, wherein the metal matrix composite comprises a metal and a non-metal.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) The system and method according to the invention will now be described in more detail with regard to the accompanying figures. The figures show one way of implementing the present invention and is not to be construed as being limiting to other possible embodiments falling within the scope of the attached claim set.

(2) FIG. 1 shows schematically and in a cross sectional view a primary coil arranged above and at a distance from an upper free surface of a volume of molten metal.

(3) FIG. 2 shows schematically a three-dimensional cross sectional view of an embodiment of the invention, where the molten metal is contained in a foundry crucible.

(4) FIG. 3 shows schematically a three-dimensional cross sectional view of an embodiment of the invention, where a secondary coil is arranged around the foundry crucible.

(5) FIG. 4 shows schematically a coil having a lower part covered by a protective coating.

(6) FIG. 5 shows schematically an embodiment of the invention, where the method is related to an additive manufacturing method.

DETAILED DESCRIPTION OF AN EMBODIMENT

(7) FIG. 1 shows schematically an example of a system for contactless induction of high-frequency vibrations in a volume of molten metal 1 during the manufacturing of a metal component or a metal matrix composite component. An electromagnetic primary coil 2 is moveably arranged above the volume of molten metal 1, and adjustment means 3 are used for adjusting the position of the primary coil 2 in relation to the upper free surface 4 of the molten metal 1. The curved/depressed shape of the upper free surface 4 shown in the figure results from the influence from the electromagnetic field as will be described below. The system further comprises a control unit 5 for controlling the position of the primary coil 2 to a predefined distance above and not in physical contact with the upper free surface 4 of the molten metal 1 during use of the system. The control unit 5 may be arranged close to the remainder of the system or at a distance therefrom. It will typically comprise a computer (not shown) which can also be used for inputting data and for monitoring the manufacturing process. The adjustment means 3 typically also comprises a sensor 6 for measuring the distance between the primary coil 2 and the upper free surface 4 of the molten metal 1 during use. In the figure, the sensor 6 is shown as arranged on the primary coil 2 for illustrative purposes only; it may also be arranged at other positions, such as directly on the part of the adjustment means 3 to which the primary coil 2 is mounted.

(8) The shape of the primary coil 2 is typically cylindrical as shown in the figures, but it can also have other shapes, such as conical or flat (pancake). The primary coil 2 preferably operates at an adjustable frequency in the order of 10 kHz and/or at a current in the order of 1 kA. The actual values will depend on the size of the application.

(9) The embodiment of the invention shown in FIG. 2 comprises a foundry crucible 7 containing at least molten metal 1 and possibly also reinforcement material, such as micro- or nano-particles or fibres. The systems shown in FIGS. 1 and 2 are used by performing the following steps: adjusting the vertical position of the primary coil 2 to a predefined distance above and not in physical contact with an upper free surface 4 of the molten metal 1, applying power to the primary coil 2 so that an electromagnetic field is obtained, adjusting the vertical position of the primary coil 2 to maintain the predefined distance, and maintaining the electromagnetic field for a predefined period of time so that a desired microstructure is obtained in the component being manufactured.

(10) The system may further comprise a feed device 8 through which material can be added to the molten metal 1 during manufacturing. In FIG. 2 this feed device 8 is in the form of a tube which is arranged so that it is surrounded by the windings of the primary coil 2. The upper end of the tube may extend e.g. to a container (not shown) containing the material to be added, or it may have a shorter length as shown in the figure.

(11) Examples of metals which can be used for manufacturing components by use of the present invention are aluminium, magnesium, titanium, zirconium, beryllium, steel, copper, nickel and cobalt. When the method is used to manufacture a metal matrix composite, the reinforcement may e.g. be made from one or more of the following materials: SiC, ZrO.sub.2, Y.sub.2O.sub.3, Al.sub.2O.sub.3, MgO, and AlN. The reinforcement will typically be in particulate form, but other types, such as fibres or platelets are also possible.

(12) In the case of composite materials, the material being added during manufacturing may be in the form of a master alloy having a high volume fraction of reinforcement. If such a masteralloy, e.g. in wire form, is added into an initially unreinforced metal, a final component having a lower volume fraction of reinforcement can be obtained in a more efficient and controllable manner than what is possible by prior art methods.

(13) When material is added to the molten metal 1 in the foundry crucible 7, the vertical position of the primary coil 2 will be adjusted accordingly so that the desired distance to the upper free surface 4 is maintained. An optimal distance may be dependent on the electromagnetic properties of the material in the foundry crucible 7, and these may depend on the composition of the material. Therefore the distance may have to be varied during addition of material, e.g. in the form of reinforcement. If the material is added in wire form, it could in principle be added without a feed device, but it is still considered advantageous to feed it via e.g. a tube in order to guide it safely to the desired point of addition to the molten metal 1 with the tube protecting both the primary coil 2 and the wire material.

(14) The primary coil 2 has to be at least vertically movable in order to adjust and optimise the distance to the upper free surface 4 of the molten metal 1. In some embodiments, such a one-direction movement is sufficient, whereas in others it is necessary that the primary coil 2 is movable in three dimensions. This will e.g. be relevant when manufacturing components of non-axisymmetric geometries where the whole volume of molten metal cannot be influenced by one horizontal position of the coil. This movability in three dimensions may also be used to move the primary coil 2 across the upper free surface 4 being so large that it cannot be sufficiently influenced by the primary coil 2 being in one horizontal position only.

(15) FIG. 3 shows another embodiment comprising a secondary low-frequency electromagnetic coil 9 arranged around the foundry crucible 7 containing the molten metal 1. This secondary coil 9 is used to induce flow and/or vibrations in the molten metal 1. The vibrations induced by the secondary coil 9 are typically in the order of 50 Hz. The main function of the secondary coil 9 is to induce flow in the melt so that molten metal passes through the ultrasonic region induced by the primary coil 2. Hereby it can be ensured that all of the material is influenced as desired. The low frequency is used is to provide penetration of the energy into larger volumes of the molten metal 1. The inclusion of such a secondary coil 9 may therefore be particularly advantageous where large volumes of metal are to be treated.

(16) The primary coil 2 will in some embodiments of the invention be provided with an insulating coating 10 at least on a part of the coil 2 being closest to the molten metal 1 during use. An example of such a coil is shown schematically in FIG. 4.

(17) In another embodiment, the invention is used for manufacturing a metal component by additive manufacturing. An example of a system for such a method is shown schematically in FIG. 5. ##The following is taken from the photam-application and amended to match the present invention##.

(18) The component 11 is being manufactured on a work surface 12 which in the illustrated embodiment can be moved in three dimensions, as indicated by arrows, while the rest of the system is not moved. In the figure, the at least one deposition material from which the component 11 is to be composed is arranged above the work surface 12. The deposition material 13 is shown in the form of one wire 13, but it could also be more wires. The deposition material is advanced to a localized deposition area 14 where it is added to the component 11 being manufactured. It is preferably passed via the central opening in the primary wire 2 as shown in the figure. As described above, it may also be advantageous to supply the wire 13 via a feed device 8, but this option is not included in FIG. 5 for clarity of the figure only. This deposition is obtained by focusing at least one energy beam 15, such as a light beam, emitted from at least one heating source 16 in the deposition area so that the deposition material 13 is deposited for building up the component 11. In the illustrated embodiment, the work surface 12 is moved in relation to the energy beam 15 and the deposition material 13 along three-dimensional paths in a way that results in the additive manufacturing of the component 11. Similar to the method as described above, the additive manufacturing method shown in FIG. 5 comprises the following steps: adjusting the vertical position of the primary coil 2 to a predefined distance above and not in physical contact with the melt-pool 16, applying power to the primary coil 2 so that an electromagnetic field is obtained, and adjusting the vertical position of the primary coil 2 to maintain the predefined distance.

(19) In this embodiment, the electromagnetic field cause melt-pool agitation and grain refinement which result in good alloy mixing, dendrite fragmentation, breaking down the grain structure to fine equiaxed grains and generally improving the mechanical properties of the component made by the additive manufacturing. The deposition material being added may e.g. be in the form of a wire, such as a wire being a master alloy as described above.

(20) To summarize, the following advantages are considered to be obtainable by at least some embodiments of the present invention:

(21) (i) It is a contactless design, so that there is no need to replace the coil element after a few runs as it is required with a sonotrode.

(22) (ii) There is no risk of contamination of the melted material due to the reaction between the melt and the coil, since there is no contact. This opens the route for high purity components as required by certain industries.

(23) (iii) Currently sonotrodes have to have a higher melting point than the metal they are treating. The new design can be applied to high temperature melts, such as the various titanium alloys now being considered for aerospace application.

(24) (iv) Electromagnetic forcing can produce strong stirring in the melt due to the Lorentz force, in contrast to the weak stirring present in acoustic streaming. This means larger volumes can be treated, or alternatively similar volumes can be treated faster than with the ultrasonic probe.

(25) (v) The induced currents tend to expel large size impurities on to the surface of the melt. In practice this means that agglomerated particles will be selectively ejected towards the energetic skin layer, where there is a higher opportunity for disaggregation. Once broken up, single NPs will be easily transported by advection.

(26) (vi) The electromagnetic coil can be scaled down to smaller sizes in order to positively influence the microstructure formation during additive manufacturing (AM), leading to better AM parts.

(27) The invention as described above may e.g. be used to produce lightweight components for use in transport and aerospace industries; especially for lightweight structural parts where high strength and stiffness are required. Nano-composites of magnesium, aluminium, titanium and beryllium are thus very desirable. Likewise, the invention can be used for the production of nanocomposites for functional materials like superconductors, magnets and thermoelectrics.

(28) Two examples of functional materials that could benefit from this invention are: (i) superconducting alloys with finely-distributed nanoparticles for flux pinning; and (ii) thermoelectric composite materials with finely-dispersed nanoparticles for improving ZT values.

(29) Although the present invention has been described in connection with the specified embodiments, it should not be construed as being in any way limited to the presented examples. The scope of the present invention is set out by the accompanying claim set. In the context of the claims, the terms comprising or comprises do not exclude other possible elements or steps. Also, the mentioning of references such as a or an etc. should not be construed as excluding a plurality. The use of reference signs in the claims with respect to elements indicated in the figures shall also not be construed as limiting the scope of the invention. Furthermore, individual features mentioned in different claims, may possibly be advantageously combined, and the mentioning of these features in different claims does not exclude that a combination of features is not possible and advantageous.