Abstract
The disclosure relates to a device for producing an investment casting component, comprising a melting chamber having an induction coil assembly disposed in the melting chamber, wherein the induction coil assembly is adapted to melt off an electrode at least partially received therein to produce a ceramic-free continuous melt jet having a melt flow rate MFR of at least 2.5 kg/min. The device further comprises a casting chamber downstream of the melting chamber and connected thereto, with an investment casting mold received or receivable therein for being filled by means of the ceramic-free, continuous melt jet.
Claims
1. A device for producing an investment casting component, comprising: a melting chamber comprising an induction coil assembly disposed in the melting chamber and adapted to melt off an electrode at least partially received therein to produce a ceramic-free continuous melt jet with a melt flow rate (MFR) of at least 2.5 kg/min; an electrode charger disposed upstream of the melting chamber and adapted to displace the electrode along its longitudinal axis in the direction of the induction coil assembly; and a casting chamber downstream of the melting chamber and connected thereto and comprising an investment casting mold received or receivable therein for being filled by means of the ceramics-free continuous melt jet.
2. The device according to claim 1, wherein the casting chamber comprises a mold heater adapted to heat the investment casting mold.
3. The device according to claim 1, wherein the induction coil assembly is operated with a power P for which the following condition is satisfied:
4. The device according to claim 1, wherein the induction coil assembly is arranged to superheat the melt jet in dependence on the melt flow rate (MFR) such that the superheat temperature (T.sub.sup) satisfies the following condition:
5. The device according to claim 1, wherein the induction coil assembly is operated with a voltage of 1200 V or less, at a frequency between 10 kHz and 300 kHz.
6. The device according to claim 1, wherein the induction coil assembly is operated with a voltage of 1200 V or less, at a frequency between 50 kHz and 200 kHz.
7. The device according to claim 1, wherein the induction coil assembly is operated with a voltage of 1200 V or less, at a frequency between 75 kHz and 125 kHz.
8. The device according to claim 1, wherein the induction coil arrangement comprises at least one induction coil comprising four windings or less.
9. The device according to claim 1, wherein the induction coil assembly comprises at least one induction coil comprising two parallel windings with a common current draw.
10. The device according to claim 1, wherein the induction coil assembly comprises a first induction coil and at least one second induction coil, wherein: the first induction coil and the second induction coil are arranged such that both induction coils serve to melt off the electrode; or the first induction coil is arranged such that it serves to melt off the electrode, and the second induction coil is arranged downstream of the first induction coil and is arranged such that it serves to heat the melt jet; or the first induction coil is arranged such that it serves to melt off the electrode, and the second induction coil is arranged upstream of the first induction coil and is arranged such that it serves to preheat the electrode to be melted off.
11. The device according to claim 1, wherein the induction coil assembly has an average coil diameter of 50 mm or more.
12. A method for producing an investment casting component, comprising: providing an electrode in a melting chamber by an electrode charger disposed upstream of the melting chamber; inserting the electrode, at least in sections, into an induction coil assembly disposed in the melting chamber; generating a ceramic-free, continuous melt jet with a melt flow rate (MFR) of at least 2.5 kg/min by feeding the electrode with the electrode charger and melting off the electrode by means of the induction coil assembly; providing an investment casting mold in a casting chamber downstream of and connected to the melting chamber; and continuously filling the investment casting mold with the melt jet.
13. The method according to claim 12, wherein the induction coil assembly is operated at a power (P) for which the following condition is satisfied:
14. The method according to claim 12, wherein by means of the induction coil assembly the melt jet is superheated as a function of the melt flow rate (MFR) such that the superheating temperature (T.sub.sup) satisfies the following condition:
15. The method according to claim 12, wherein the melt jet is superheated by means of the induction coil assembly by at least 10 C.
16. The method according to claim 12, wherein the induction coil assembly is operated at a voltage of 1200 V or less and at a frequency between 10 kHz and 300 kHz.
17. The method according to claim 12, wherein the induction coil assembly is operated at a voltage of 1200 V or less and at a frequency between 50 kHz and 200 kHz.
18. The method according to claim 12, wherein the induction coil assembly is operated at a voltage of 1200 V or less and at a frequency between 75 kHz and 125 kHz.
19. The method according to claim 12, wherein at least the melting chamber is pressurized with an absolute pressure of at least 30 mbar so that the melt jet is generated under this absolute pressure.
20. A device for producing an investment casting component, comprising: a melting chamber comprising an induction coil assembly disposed in the melting chamber and adapted to melt off an electrode at least partially received therein to produce a ceramic-free continuous melt jet with a melt flow rate (MFR) of at least 2.5 kg/min; an electrode charger disposed upstream of the melting chamber and adapted to displace the electrode along its longitudinal axis in the direction of the induction coil assembly; and a casting chamber downstream of the melting chamber and connected thereto and comprising an investment casting mold received or receivable therein for being filled by means of the ceramics-free continuous melt jet; wherein the induction coil assembly is arranged to superheat the melt jet in dependence on the melt flow rate (MFR) such that the superheat temperature (T.sub.sup) satisfies the following condition:
Description
BRIEF DESCRIPTION OF THE FIGURES
(1) Exemplary embodiments of the present disclosure are explained in more detail below with reference to the accompanying schematic drawing. In the drawing:
(2) FIG. 1 is a schematic sectional view of a device according to one embodiment of the disclosure;
(3) FIG. 2A is a schematic representation of an embodiment of an induction coil according to the disclosure for the device of FIG. 1;
(4) FIG. 2B is a schematic sectional view of the induction coil of FIG. 2A in operation;
(5) FIG. 3 is a schematic representation of a first embodiment of an induction coil assembly according to the disclosure in operation;
(6) FIG. 4 is a schematic representation of a second embodiment of an induction coil assembly according to the disclosure in operation;
(7) FIG. 5 is a schematic representation of a third embodiment of an induction coil assembly according to the disclosure in operation;
(8) FIG. 6 is a diagram showing the relationship between superheating temperature and melt flow rate in a device according to the disclosure for different electrode materials;
(9) FIG. 7 is a diagram showing the relationship between voltage and melt flow rate in a device according to the disclosure for different electrode materials;
(10) FIG. 8 is a diagram showing the relationship between power and melt flow rate in a device according to the disclosure for different electrode materials;
(11) FIG. 9 is a diagram showing the relationship between superheating temperature and melt flow rate in devices according to the disclosure with different induction coil designs;
(12) FIG. 10 is a diagram showing the relationship between voltage and melt flow rate in devices according to the disclosure with different induction coil designs; and
(13) FIG. 11 is a diagram showing the relationship between power and melt flow rate in devices according to the disclosure with different induction coil designs.
DESCRIPTION OF THE FIGURES
(14) FIG. 1 shows a device or plant 10 for producing investment casting components. The device 10 comprises a melting chamber 12 comprising an induction coil assembly 14 mounted in the melting chamber 12. A vacuum is applied to the melting chamber 12. Alternatively, the melting chamber 12 may be pressurized with an inert gas atmosphere.
(15) Above the melting chamber 12, i.e. upstream thereof, an electrode charger 16 is disposed. This comprises an electrode 18 that can be displaced along its longitudinal axis in the direction of the induction coil assembly 14 and can be rotated about its longitudinal axis by means of the electrode charger 16. In this embodiment, the electrode 18 is an electrode made of a titanium alloy. It is understood that electrodes of other metals or metal alloys may likewise be provided. The electrode 18 is inserted into the induction coil assembly 14 at least in sections, more specifically with a lower end portion, during operation of the plant.
(16) The induction coil assembly 14 is adapted to melt the electrode 18 off in order to produce a ceramic-free continuous melt jet (not shown in FIG. 1, but see, for example, FIG. 2B). Feeding the electrode 18, as well as rotating the electrode 18 by means of the electrode charger 16, can ensure uniform melting of the electrode 18 and a generation of a substantially uninterrupted, continuous melt jet.
(17) The induction coil assembly 14 is operated or controlled to melt off the electrode 18 and to generate a continuous melt jet with a melt flow rate MFR of at least 2.5 kg/min, such as between 2.5 kg/min and 10 kg/min.
(18) The device 10 further comprises a casting chamber 20 which is disposed downstream of the melting chamber 12, i.e. arranged below the latter, and is connected to the melting chamber 12 in a pressure-tight manner. The casting chamber 20 is adapted to receive an investment casting mold (not shown here) that is filled with the melt jet during operation. The investment casting mold may have any shape, depending on the investment casting to be produced. In some implementations, the investment casting mold may be a ceramic mold.
(19) The casting chamber 20 includes a mold heater 22. The mold heater 22 is used to heat an investment casting mold provided in the casting chamber 20 prior to the start of the melting process or a melting sequence. In addition, the mold heater 22 can be used to further heat the investment casting mold during melting and filling. This can prevent the melt from solidifying too early and upon contact with the wall of the investment casting mold, which would negatively affect the quality of the investment casting component.
(20) Below the casting chamber 20, an loading/unloading chamber 24 of the device 10 is formed, which is connected to the casting chamber 20. The loading/unloading chamber 24 is used for inserting the investment casting mold and removing the cast investment casting component.
(21) A mold extractor 26 is formed in the loading/unloading chamber 24, by means of which the investment casting mold can be extracted in a direction away from the melting chamber 12.
(22) FIG. 1 also shows a maintenance platform 28 formed at the device 10 and an operating platform 29 formed at the apparatus 10.
(23) FIGS. 2A and 2B show an embodiment of an induction coil 30 of the induction coil assembly 14 of FIG. 1. As can be seen in the perspective view of FIG. 2A, the induction coil 30 in this embodiment is formed as a 22-windings induction coil. That is, the induction coil 30 comprises two parallel two-windings winding arrangements. The windings 32 to 38 have a common current draw (not shown). The current flow through the induction coil 30, or more precisely its equal division due to the parallel connection, is shown in FIG. 2A by lines 40 and 42. Moreover, the uniform distribution of the current is indicated in FIG. 2B by the different patterns of the cross-sections of the windings 32 to 38. As can be seen from FIGS. 2A and 2B, windings 32 and 38 are connected in series and in parallel with windings 34 and 36, which (i.e. windings 34 and 36) in turn are connected in series.
(24) By use of the 22-windings coil configuration shown in FIGS. 2A and 2B, a uniform power input to the electrode 18 to be melted off can be achieved. It is understood that in other embodiments of the disclosure other coil configurations may be provided. In some implementations, two-windings, three-windings or four-windings coil configurations without parallel windings may be provided. Alternatively, single-winding coil configurations with or without parallel connection of windings may be provided (an induction coil with two or more parallel single-winding winding arrangements may nevertheless be referred to herein as a single-winding coil).
(25) In addition to the coil configuration, FIG. 2B also shows the electrode 18 inserted into the induction coil 30 in sections and melted off at a lower end by means of the induction coil 30, thereby producing a continuous melt jet 40.
(26) Different induction coil assemblies 114, 214 and 314 are shown in FIGS. 3 to 5. Each of these induction coil assemblies 114, 214, 314 comprises in the embodiments shown, in addition to the induction coil 30, a further induction coil 50, which are only schematically indicated in FIGS. 3 to 5. They can each be a single- or multi-windings configuration and have the same or a different number of windings. The two induction coils 30, 50 are formed and controlled separately from each other in the induction coil assemblies 114, 214, 314 shown. They each have their own power supply. In the embodiments shown, the induction coil 30 is operated at a power P1, a frequency f1, and a voltage U1 (here, for example, U11000 V, P1500 kW, f1350 kHz). The second induction coil 50 is operated at a power P2, a frequency f2 and a voltage U2 (here, for example, U21000 V, P2500 kW, f2350 kHz).
(27) In the embodiment shown in FIG. 3, both induction coils 30, 50 are arranged such that they both serve to melt off the electrode 18. The induction coils 30, 50 are arranged side by side. In the cross-sectional view shown, the adjacent winding cross-sections of both induction coils are arranged substantially parallel to an inclined surface of the melted off end portion of the electrode 18. Both induction coils 30, 50 have a conical shape in FIG. 3. The two induction coils 30, 50 are here embedded in a soft magnetic yoke 52, whereby an undesired coil interaction is prevented. By means of such an embodiment, the generated melt flow rate MFR can be increased by increasing the powers P1 and P2 of the two induction coils 30, 50.
(28) In the embodiment shown in FIG. 4, the first induction coil 30 is arranged such that it serves to melt off the electrode 18. The second induction coil 50 is arranged downstream of the first induction coil and is arranged such that it serves to heat the already melted melt jet 40. The winding/s of the first induction coil 30 are arranged substantially parallel to the inclined surface of the melted off end portion of the electrode 18. The first induction coil 30 has a conical shape. The downstream second induction coil 50 has a cylindrical shape and encloses the melt jet 40 in sections. The second induction coil 50 is embedded in a soft magnetic yoke 52. By means of such an embodiment, the superheating of the generated melt jet can be further increased by increasing the power P2 of the second induction coil 50.
(29) In the embodiment shown in FIG. 5, the first induction coil 30 is arranged such that it serves to melt off the electrode 18. The second induction coil 50 is located upstream of the first induction coil 30 and is arranged such that it serves to preheat the electrode 18 to be melted. For this purpose, the windings of the first induction coil 30 are arranged substantially parallel to the inclined surface of the melted end portion of the electrode 18. Here, too, the first induction coil 30 has a conical shape. The upstream second induction coil 50 has a cylindrical shape and encloses the electrode 18 in sections, more precisely a part of the electrode 18 which has not yet been melted off. The second induction coil 50 is embedded in a soft magnetic yoke 52. By means of such an embodiment, the superheating of the generated melt jet can be further increased by increasing the power P2 of the second induction coil 50. In addition, the upstream second induction coil 50 may also contribute at least slightly to the generation of the melt jet, so that an increase in P1 and P2 may contribute to an increase in the melt flow rate MFR.
(30) FIG. 6 shows a diagram illustrating a determined relationship between the superheating temperature T.sub.sup [ C.] of the melt jet and the melt flow rate MFR [kg/min] in a device 10 according to the disclosure comprising a two-windings induction coil. Line A1 shows the relationship for an electrode 18 made of Ti64. Line A2 shows the relationship for an electrode 18 made of IN718. As can be seen, sufficient superheating can be achieved at a melt flow rate of at least 2.5 kg/min.
(31) FIG. 7 shows a diagram illustrating a determined relationship between the voltage U [V] at which the induction coil is operated and the melt flow rate MFR [kg/min] in a device 10 according to the disclosure comprising a two-windings induction coil. Line B1 shows the relationship for an electrode 18 made of Ti64. Line B2 shows the relationship for an electrode 18 made of IN718.
(32) FIG. 8 shows a diagram illustrating a determined relationship between the power P [kW] at which the induction coil is operated and the melt flow rate MFR [kg/min] in a device 10 according to the disclosure comprising a two-windings induction coil. Line C1 shows the relationship for an electrode 18 made of Ti64. Line C2 shows the relationship for an electrode 18 made of IN718.
(33) FIG. 9 shows a diagram illustrating a determined relationship between the superheating temperature T.sub.sup [ C.] of the melt jet and the melt flow rate MFR [kg/min] in devices 10 according to the disclosure comprising different induction coil designs. More specifically, the relationship is shown here for induction coil designs with different numbers of windings. Line D1 shows the relationship for a two-windings induction coil for generating the melt jet (without windings connected in parallel). Line D2 shows the relationship for a three-windings induction coil for generating the melt jet (without windings connected in parallel). Line D3 shows the relationship for a four-windings induction coil for generating the melt jet (without windings connected in parallel). As can be seen, a larger superheating temperature T.sub.sup can be achieved with the same melt flow rate MFR by using a smaller number of windings in the induction coil.
(34) FIG. 10 shows a diagram illustrating a determined relationship between the voltage U [V] with which the induction coil is operated and the melt flow rate MFR [kg/min] in devices 10 according to the disclosure with different induction coil designs. More precisely, the relationship is shown here for induction coil designs with different numbers of windings. Line E1 shows the relationship for a two-windings induction coil for generating the melt jet (without windings connected in parallel). Line E2 shows the relationship for a three-windings induction coil for generating the melt jet (without windings connected in parallel). Line E3 shows the relationship for a four-windings induction coil for generating the melt jet (without windings connected in parallel). As can be seen, with a lower number of windings in the induction coil, a lower voltage U is required for generating the same melt flow rate MFR.
(35) FIG. 11 shows a diagram illustrating a determined relationship between the power P [kW] with which the induction coil is operated and the melt flow rate MFR [kg/min] in devices 10 according to the disclosure with different induction coil designs. More precisely, the relationship is shown here for induction coil designs with different numbers of windings. Line F1 shows the relationship for a two-windings induction coil for generating the melt jet (without windings connected in parallel). Line F2 shows the relationship for a three-windings induction coil for generating the melt jet (without windings connected in parallel). Line F3 shows the relationship for a four-winding induction coil for generating the melting beam (without windings connected in parallel). As can be seen, the different number of windings of the induction coil has no significant effect on the power P required to be applied to generate a given melt flow rate MFR.
(36) The diagrams in FIGS. 9 to 11 refer to an electrode used made of IN718 with an electrode diameter of 150 mm.
(37) The frequency of the induction coil set for FIGS. 6 to 11 is 100 kHz.
LIST OF REFERENCE SYMBOLS
(38) 10 device 12 melting chamber 14, 114, 214, 314 induction coil assemblies 16 electrode charger 18 electrode 20 casting chamber 22 mold heater 24 loading/unloading chamber 26 mold extractor 28 maintenance platform 29 operating platform 30 induction coil 32, 34, 36, 38 windings 40, 42 melt jet 50 second induction coil 52 soft magnetic yoke
