METHOD OF TAPPING MOLTEN METAL AND APPARATUS FOR TAPPING MOLTEN METAL

Abstract

A method and apparatus for tapping molten metal are provided. The apparatus includes a tapping chamber, a molten metal holding chamber, a regulation part for allowing or shutting off transfer of the molten metal from the holding chamber into the tapping chamber, a tapping channel at the tapping chamber for tapping the molten metal outside, and a gas supply part capable of supplying gas from outside into the tapping chamber. The method includes transferring the molten metal by natural flow down due to difference in level of the molten metal between the holding chamber and the tapping chamber or by pressure of gas supplied through a pressurizing part capable of supplying gas from outside into the holding chamber. The method further includes tapping the molten metal in the tapping chamber though the tapping channel into a target place by pressure of gas supplied through the gas supply part.

Claims

1. A method of tapping molten metal using tapping apparatus, the tapping apparatus comprising: a tapping chamber for tapping molten metal, a molten metal holding chamber in communication with the tapping chamber, for holding the molten metal therein, a regulation part located between the molten metal holding chamber and the tapping chamber for allowing or shutting off transfer of the molten metal from the molten metal holding chamber into the tapping chamber, a tapping channel placed at the tapping chamber for tapping the molten metal in the tapping chamber outside, and a gas supply part capable of supplying gas from outside into the tapping chamber, the method comprising: (1) at least either of transferring, with transfer of the molten metal allowed by the regulation part, the molten metal in the molten metal holding chamber into the tapping chamber by natural flow down due to difference in level of the molten metal between the molten metal holding chamber and the tapping chamber, and transferring, with the transfer of the molten metal allowed by the regulation part, the molten metal in the molten metal holding chamber into the tapping chamber by pressure of gas supplied through a pressurizing part which is capable of supplying gas from outside and into the molten metal holding chamber, and (2) tapping, with the transfer of the molten metal shut off by the regulation part, the molten metal in the tapping chamber though an interior of the tapping channel into a target place by pressure of gas supplied through the gas supply part.

2. The method of tapping molten metal according to claim 1, comprising: (3) after the tapping, at least either of transferring, with transfer of the molten metal allowed by the regulation part, the molten metal in the molten metal holding chamber into the tapping chamber by natural flow down due to the difference in level of the molten metal between the molten metal holding chamber and the tapping chamber, and transferring, with the transfer of the molten metal allowed by the regulation part, the molten metal in the molten metal holding chamber into the tapping chamber by pressure of gas supplied through the pressurizing part, and (4) tapping, with the transfer of the molten metal shut off by the regulation part, the molten metal in the tapping chamber though an interior of the tapping channel into a target place by pressure of gas supplied through a gas supply part, (5) wherein one cycle of steps (3) and (4) is performed or a plurality of cycles of steps (3) and (4) are repeated.

3. A method of tapping molten metal using tapping apparatus, the tapping apparatus comprising: a tapping chamber for tapping molten metal, a molten metal holding chamber in communication with the tapping chamber, for holding the molten metal therein, a regulation part located between the molten metal holding chamber and the tapping chamber for allowing or shutting off transfer of the molten metal from the molten metal holding chamber into the tapping chamber, a tapping channel placed at the tapping chamber for tapping the molten metal in the tapping chamber outside, and a gas supply/exhaust part capable of supplying gas under pressure from outside into the tapping chamber, and exhausting gas from the tapping chamber for depressurizing, the method comprising: (6) at least either of transferring, with transfer of the molten metal allowed by the regulation part, the molten metal in the molten metal holding chamber into the tapping chamber by natural flow down due to difference in level of the molten metal between the molten metal holding chamber and the tapping chamber, and transferring, with the transfer of the molten metal allowed by the regulation part, the molten metal in the molten metal holding chamber into the tapping chamber by exhausting gas through the gas supply/exhaust part, and (7) tapping, with the transfer of the molten metal shut off by the regulation part, the molten metal in the tapping chamber though an interior of the tapping channel into a target place by supplying gas under pressure through the gas supply/exhaust part.

4. The method of tapping molten metal according to claim 3, comprising: (8) after the tapping, at least either of transferring, with transfer of the molten metal allowed by the regulation part, the molten metal in the molten metal holding chamber into the tapping chamber by natural flow down due to the difference in level of the molten metal between the molten metal holding chamber and the tapping chamber, and transferring, with the transfer of the molten metal allowed by the regulation part, the molten metal in the molten metal holding chamber into the tapping chamber by exhausting the gas from and depressurizing the tapping chamber through the gas supply/exhaust part, and (9) tapping, with the transfer of the molten metal shut off by the regulation part, the molten metal in the tapping chamber though an interior of the tapping channel into a target place by supplying gas under pressure through the gas supply/exhaust part, (10) wherein one cycle of steps (8) and (9) is performed or a plurality of cycles of steps (8) and (9) are repeated.

5. The method of tapping molten metal according to claim 1, wherein, when the level of the molten metal in the molten metal holding chamber is lower than the level of the molten metal in the tapping chamber, with the transfer of the molten metal allowed by the regulation part, the molten metal in the molten metal holding chamber is transferred into the tapping chamber by the pressure of the gas supplied through the pressurizing part of the molten metal holding chamber.

6. The method of tapping molten metal according to claim 3, wherein, when the level of the molten metal in the molten metal holding chamber is lower than the level of the molten metal in the tapping chamber, with the transfer of the molten metal allowed by the regulation part, the molten metal in the molten metal holding chamber is transferred into the tapping chamber by exhausting the gas from the tapping chamber through the gas supply/exhaust part.

7. The method of tapping molten metal according to claim 1, wherein a volume of the tapping chamber is smaller than a volume of the molten metal holding chamber.

8. The method of tapping molten metal according to claim 1, wherein transition from the transferring to the tapping is made triggered by lowering of the level of the molten metal in the molten metal holding chamber.

9. Apparatus for tapping molten metal, comprising: a tapping chamber for tapping molten metal, a molten metal holding chamber in communication with the tapping chamber, for holding the molten metal therein, a regulation part located between the molten metal holding chamber and the tapping chamber for allowing or shutting off transfer of the molten metal from the molten metal holding chamber into the tapping chamber, a tapping channel placed at the tapping chamber for tapping the molten metal in the tapping chamber outside, a gas supply part capable of supplying gas from outside into the tapping chamber, and a control section, wherein the control section is configured to control: (11) at least either of transferring, with transfer of the molten metal allowed by the regulation part, the molten metal in the molten metal holding chamber into the tapping chamber by natural flow down due to difference in level of the molten metal between the molten metal holding chamber and the tapping chamber, and transferring, with a compression part and with the transfer of the molten metal allowed by the regulation part, the molten metal in the molten metal holding chamber into the tapping chamber by pressure of gas supplied through a pressurizing part which is capable of supplying gas from outside and into the molten metal holding chamber, and (12) tapping, with the transfer of the molten metal shut off by the regulation part, the molten metal in the tapping chamber though an interior of the tapping channel into a target place by pressure of gas supplied through a gas supply part.

10. The apparatus for tapping molten metal according to claim 9, wherein the control section causes: (13) after the tapping, at least either of transferring, with transfer of the molten metal allowed by the regulation part, the molten metal in the molten metal holding chamber into the tapping chamber by natural flow down due to the difference in level of the molten metal between the molten metal holding chamber and the tapping chamber, and transferring, with the transfer of the molten metal allowed by the regulation part, the molten metal in the molten metal holding chamber into the tapping chamber by pressure of gas supplied through the pressurizing part, and (14) tapping, with the transfer of the molten metal shut off by the regulation part, the molten metal in the tapping chamber though an interior of the tapping channel into a target place by pressure of gas supplied through a gas supply part, (15) wherein one cycle of steps (13) and (14) is performed or a plurality of cycles of steps (13) and (14) are repeated.

11. An apparatus for tapping molten metal, comprising: a tapping chamber for tapping molten metal, a molten metal holding chamber in communication with the tapping chamber, for holding the molten metal therein, a regulation part located between the molten metal holding chamber and the tapping chamber for allowing or shutting off transfer of the molten metal from the molten metal holding chamber into the tapping chamber, a tapping channel placed at the tapping chamber for tapping the molten metal in the tapping chamber outside, a gas supply/exhaust part capable of supplying gas under pressure from outside into the tapping chamber, and exhausting gas from the tapping chamber for depressurizing, and a control section, wherein the control section is configured to control: (16) at least either of transferring, with transfer of the molten metal allowed by the regulation part, the molten metal in the molten metal holding chamber into the tapping chamber by natural flow down due to difference in level of the molten metal between the molten metal holding chamber and the tapping chamber, and transferring, with the transfer of the molten metal allowed by the regulation part, the molten metal in the molten metal holding chamber into the tapping chamber by exhausting gas through the gas supply/exhaust part, and (17) tapping, with the transfer of the molten metal shut off by the regulation part, the molten metal in the tapping chamber through an interior of the tapping channel into a target place by supplying gas under pressure through the gas supply/exhaust part.

12. The apparatus for tapping molten metal according to claim 11, wherein the control section causes: (18) after the tapping, at least either of transferring, with transfer of the molten metal allowed by the regulation part, the molten metal in the molten metal holding chamber into the tapping chamber by natural flow down due to the difference in level of the molten metal between the molten metal holding chamber and the tapping chamber, and transferring, with the transfer of the molten metal allowed by the regulation part, the molten metal in the molten metal holding chamber into the tapping chamber by exhausting the gas from and depressurizing the tapping chamber through the gas supply/exhaust part, and (19) tapping, with the transfer of the molten metal shut off by the regulation part, the molten metal in the tapping chamber though an interior of the tapping channel into a target place by supplying gas under pressure through the gas supply/exhaust part, (20) wherein one cycle of steps (18) and (19) is performed or a plurality of cycles of steps (18) and (19) are repeated.

13. The method of tapping molten metal according to claim 3, wherein a volume of the tapping chamber is smaller than a volume of the molten metal holding chamber.

14. The method of tapping molten metal according to claim 3, wherein transition from the transferring to the tapping is made triggered by lowering of the level of the molten metal in the molten metal holding chamber.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0054] FIG. 1 illustrates a tapping furnace according to the first embodiment in a schematic sectional view taken along lines Z1-Z1 in FIG. 32 to be discussed later.

[0055] FIG. 2 is a schematic view of the first embodiment of FIG. 1 illustrating the state immediately after the completion of transfer of the molten metal from the molten metal holding chamber into the tapping chamber.

[0056] FIG. 3 is a schematic view of the first embodiment, wherein the transfer of the molten metal of FIG. 2 is shut off with the regulation part.

[0057] FIG. 4 is a schematic view of the first embodiment illustrating the state immediately after the completion of tapping of the molten metal through the tapping channel by supplying gas under pressure through the gas supply part.

[0058] FIG. 5 is a schematic view of the first embodiment, wherein the transfer of the molten metal is allowed from the state of FIG. 4, wherein the transfer of the molten metal is shut off by the regulation part.

[0059] FIG. 6 is a schematic view of the first embodiment, wherein the transfer of the molten metal is shut off with the regulation part, after the completion of the transfer of the molten metal from the molten metal holding chamber into the tapping chamber from the state of FIG. 5.

[0060] FIG. 7 is a schematic view of the first embodiment illustrating the state immediately after the completion of tapping of the molten metal through the tapping channel by supplying gas under pressure through the gas supply part from the state of FIG. 6.

[0061] FIG. 8 is a schematic view of a modification of the first embodiment having a melt level sensor which indicates the lower limit level of the molten metal, below which the molten metal heaters are exposed on the surface of the molten metal in the molten metal holding chamber and operated without molten metal therearound, and illustrates the states immediately after the completion of supplying gas under pressure through the compression part and transferring the molten metal in the molten metal holding chamber into the tapping chamber.

[0062] FIG. 9 illustrates a tapping furnace according to the second embodiment in a schematic sectional view taken along lines Z1-Z1 in FIG. 32 to be discussed later.

[0063] FIG. 10 is a schematic view of the second embodiment of FIG. 9 illustrating the state immediately after the completion of transfer of the molten metal from the molten metal holding chamber into the tapping chamber.

[0064] FIG. 11 is a schematic view of the second embodiment, wherein the transfer of the molten metal of FIG. 10 is shut off with the regulation part.

[0065] FIG. 12 is a schematic view of the second embodiment illustrating the state immediately after the completion of tapping of the molten metal through the tapping channel by supplying gas under pressure through the gas supply part.

[0066] FIG. 13 is a schematic view of the second embodiment, wherein the transfer of the molten metal is allowed from the state of FIG. 12, wherein the transfer of the molten metal is shut off by the regulation part.

[0067] FIG. 14 is a schematic view of the second embodiment, wherein the transfer of the molten metal is shut off with the regulation part, after the completion of the transfer of the molten metal from the molten metal holding chamber into the tapping chamber from the state of FIG. 13.

[0068] FIG. 15 is a schematic view of the second embodiment illustrating the state immediately after the completion of tapping of the molten metal through the tapping channel by supplying gas under pressure through the gas supply part from the state of FIG. 14.

[0069] FIG. 16 illustrates a tapping furnace according to the third embodiment in a schematic sectional view taken along lines Z1-Z1 in FIG. 34 to be discussed later.

[0070] FIG. 17 is a schematic view of the third embodiment of FIG. 16 illustrating the state immediately after the completion of transfer of the molten metal from the molten metal holding chamber into the tapping chamber.

[0071] FIG. 18 is a schematic view of the third embodiment, wherein the transfer of the molten metal of FIG. 17 is shut off with the regulation part.

[0072] FIG. 19 is a schematic view of the third embodiment illustrating the state immediately after the completion of tapping of the molten metal through the tapping channel by supplying gas under pressure through the gas supply part.

[0073] FIG. 20 is a schematic view of the third embodiment, wherein the transfer of the molten metal is allowed from the state of FIG. 19, wherein the transfer of the molten metal is shut off by the regulation part.

[0074] FIG. 21 is a schematic view of the third embodiment, wherein the transfer of the molten metal is shut off with the regulation part, after the completion of the transfer of the molten metal from the molten metal holding chamber into the tapping chamber from the state of FIG. 20.

[0075] FIG. 22 is a schematic view of the third embodiment illustrating the state immediately after the completion of tapping of the molten metal through the tapping channel by supplying gas under pressure through the gas supply/exhaust part from the state of FIG. 21.

[0076] FIG. 23 is a schematic view of a modification of the third embodiment having a melt level sensor which indicates the lower limit level of the molten metal, below which the molten metal heaters are exposed on the surface of the molten metal in the molten metal holding chamber and operated without molten metal therearound, and illustrates the states immediately after the completion of exhausting the gas through the gas supply/exhaust part and transferring the molten metal in the molten metal holding chamber into the tapping chamber.

[0077] FIG. 24 illustrates a tapping furnace according to the fourth embodiment in a schematic sectional view taken along lines Z1-Z1 in FIG. 34 to be discussed later.

[0078] FIG. 25 is a schematic view of the fourth embodiment of FIG. 24 illustrating the state immediately after the completion of transfer of the molten metal from the molten metal holding chamber into the tapping chamber.

[0079] FIG. 26 is a schematic view of the fourth embodiment, wherein the transfer of the molten metal of FIG. 25 is shut off with the regulation part.

[0080] FIG. 27 is a schematic view of the fourth embodiment illustrating the state immediately after the completion of tapping of the molten metal through the tapping channel by supplying gas under pressure through the gas supply/exhaust part.

[0081] FIG. 28 is a schematic view of the fourth embodiment, wherein the transfer of the molten metal is allowed from the state of FIG. 27, wherein the transfer of the molten metal is shut off by the regulation part.

[0082] FIG. 29 is a schematic view of the fourth embodiment, wherein the transfer of the molten metal is shut off with the regulation part, after the completion of the transfer of the molten metal from the molten metal holding chamber into the tapping chamber from the state of FIG. 28.

[0083] FIG. 30 is a schematic view of the fourth embodiment illustrating the state immediately after the completion of tapping of the molten metal through the tapping channel by supplying gas under pressure through the gas supply/exhaust part from the state of FIG. 29.

[0084] FIG. 31 illustrates a modification of the penetration position of the tapping channel (e.g., a tapping pipe), and a modification of the regulation part, in a schematic view.

[0085] FIG. 32 is a plan view of the tapping furnace according to the first or second embodiment.

[0086] FIG. 33 is a plan view of the tapping furnace according to the modification of the first embodiment.

[0087] FIG. 34 is a plan view of the tapping furnace according to the third or fourth embodiment.

[0088] FIG. 35 is a plan view of the tapping furnace according to the modification of the third embodiment.

EMBODIMENTS FOR CARRYING OUT THE INVENTION

[0089] Embodiments of the present invention will now be discussed.

[0090] Preferred embodiments of the tapping furnace 1 according to the present invention will now be discussed with reference to the drawings. Note that the discussions below and the attached drawings are merely an example of embodiments according to the present invention, which should not be interpreted as being limited to such embodiments.

[0091] FIGS. 1 to 7 illustrate the first embodiment, and FIG. 8 illustrates a modification thereof. FIGS. 9 to 15 illustrate the second embodiment. FIGS. 16 to 22 illustrate the third embodiment, and FIG. 23 illustrates a modification thereof. FIGS. 24 to 30 illustrate the fourth embodiment. The first and second embodiments are embodiments of the first aspect mentioned above, and the third and fourth embodiments are embodiments of the second aspect mentioned above.

[0092] FIG. 31 shows a modification of the regulation part 4 and a modification of the penetration position of the tapping channel 3 (e.g., tapping pipe 6). The open arrows in FIGS. 4, 7, 12, 13, 15, 19, 22, 23, 27, and 30 indicate pressurizing or depressurizing of gas through the pressurizing part 13A, the gas supply part 16A, and the gas supply/exhaust part 16G, and tapping of molten metal MM through the tapping channel 3. The broken lines in FIGS. 2, 4, 6-8, 10, 12, 14, 15, 17, 19, 21-23, 25, 27, 29, and 30 indicates the level of the molten metal MM before transferring. The arrows in broken lines in FIGS. 32 to 35 indicate the signals sent from the control section 50 to the tapping furnace 1.

First Embodiment

[0093] The first embodiment of the tapping furnace 1 according to the present invention is shown in FIGS. 1 to 8. The tapping furnace 1 has a molten metal holding chamber 13 for receiving and holding therein molten metal MM of e.g., an aluminum alloy, and a tapping chamber 16 for tapping the molten metal MM, and the molten metal holding chamber 13 and the tapping chamber 16 communicate via a molten metal communication channel 5.

[0094] The molten metal communication channel 5 is provided with a regulation part 4 for allowing or shutting off transfer of the molten metal MM from the molten metal holding chamber 13 to the tapping chamber 16.

<Molten Metal Holding Chamber>

[0095] The molten metal holding chamber 13 is an interior space of a molten metal holding chamber vessel 13D, and the molten metal MM is held in the molten metal holding chamber 13. For heating the molten metal MM in the molten metal holding chamber 13 or keeping the temperature of the molten metal MM in the molten metal holding chamber 13 from falling, a molten metal heating unit 2 is provided. The molten metal holding chamber 13 is provided in its upper part US with an upper lid 13C of the molten metal holding chamber for closing an upper opening of the molten metal holding chamber 13, and a lid 13B of a molten metal supply port, through which the molten metal MM is supplied from outside the tapping furnace 1. The upper lid 13C of the molten metal holding chamber is equipped with a melt level sensor 13E.

[0096] In the illustrated embodiment, by providing the lid 13B of the molten metal supply port, the molten metal MM may be supplied from outside the tapping furnace 1 using a ladle or the like. The manner of supplying molten metal MM from outside the tapping furnace 1 is not limited to this. Though not shown, for example, a gutter may be provided through a side wall of the tapping furnace 1 defining the molten metal holding chamber 13. The gutter may be communicated with a melting furnace or a buffer furnace outside the tapping furnace 1 to supply the molten metal MM in the melting furnace or the buffer furnace via the gutter into the molten metal holding chamber 13. Alternatively, the molten metal holding chamber 13 per se may be given a melting function to directly melt therein ingots, return scraps, or scraps (e.g., briquette material or machined chips) to produce molten metal MM.

[0097] The molten metal heating unit 2 is not particularly limited, and may preferably be those do not disturb the transfer of the molten metal MM, and an elongate cylindrical heater is preferred rather than a plate-shaped heater. Specifically, heaters in a tubular shape, such as tube burners or tube heaters, are preferred. Any number of the molten metal heating units 2 may be provided without limitation, as long as the temperature of the molten metal MM is properly maintained. In the illustrated embodiment, for example, three of the molten metal heating units 2 are provided in the molten metal holding chamber 13.

[0098] In the illustrated embodiment, the lower end of the melt level sensor 13E is set at the same level as the lower end of a melt level sensor 16E of the tapping chamber 16 to be discussed later. This is for alerting timing for supplying the molten metal MM from outside the tapping furnace 1 into the molten metal holding chamber 13, when the amount of the molten metal in the molten metal holding chamber 13 decreases gradually while the transfer from the molten metal holding chamber 13 into the tapping chamber 16 and the tapping from the tapping chamber 16 of the molten metal MM are repeated by natural flow down due to difference in level of the molten metal MM between the molten metal holding chamber 13 and the tapping chamber 16, and the transfer of the molten metal MM from the molten metal holding chamber 13 into the tapping chamber 16 by natural flow down is becoming harder, and finally the molten metal surface is disengaged from the lower end of the melt level sensor 13E (i.e., when the molten metal MM can no longer be transferred by natural flow down from the molten metal holding chamber 13 into the tapping chamber 16).

[0099] When the timing for supplying the molten metal is reached, the lid 13B of the molten metal supply port 13B is opened, and the molten metal MM is supplied through the port. In order to detect the upper limit of the molten metal to be supplied, another melt level sensor 13F may be installed in addition to the melt level sensor 13E for detecting the lower limit of the amount of the molten metal.

[0100] The molten metal holding chamber 13 may be provided with a pressurizing part 13A, through which dry air or inert gas (nitrogen gas, argon gas, or the like) may be supplied under pressure.

[0101] In other words, with the molten metal communication channel 5 opened by the regulation part 4 in advance, by pressurizing the interior of the molten metal holding chamber 13, the molten metal MM may efficiently be transferred from the molten metal holding chamber 13 via the molten metal communication channel 5 into the tapping chamber 16 until the melt level sensor 16E of the tapping chamber 16 detects the surface of the molten metal MM.

<Tapping Chamber>

[0102] The tapping chamber 16 is an interior space of a tapping chamber vessel 16D, and the molten metal MM is retained in the tapping chamber 16. The tapping chamber 16, according to the first embodiment, is provided with a gas supply part 16A for use in tapping the molten metal MM transferred from the molten metal holding chamber 13 into the tapping chamber 16.

[0103] For forming a tapping channel 3 for tapping the molten metal MM in the tapping chamber 16, a tapping pipe 6 penetrating a wall of the tapping chamber 16 may be used. Use of the tapping pipe 6 allows positioning of a tapping port in the lower part of the tapping chamber 16. The tapping channel 3 may alternatively be a mere opening through the wall of the tapping chamber 16.

[0104] For heating the molten metal MM in the tapping chamber 16 or keeping the temperature of the molten metal MM in the tapping chamber 16 from falling, a molten metal heating unit 2 may preferably be provided. The tapping chamber 16 is provided in its upper part US with a tapping chamber lid 16C for closing the tapping chamber 16. The tapping chamber lid 16C can achieve complete sealing of the tapping chamber, and is provided with a melt level sensor 16E and a thermocouple 16B.

[0105] The molten metal heating unit 2 is not particularly limited, and may be similar to those installed in the molten metal holding chamber 13. In the illustrated embodiment, for example, one molten metal heating unit 2 is provided in the tapping chamber 16.

[0106] According to the first embodiment, FIG. 1 indicates the relationship in molten metal surface, wherein the level of the molten metal MM in the molten metal holding chamber 13 is higher than the level of the molten metal MM in the tapping chamber 16. With this difference in level of the molten metal, the method of the present embodiment includes a transferring step of at least either of: transferring the molten metal MM in the molten metal holding chamber 13 into the tapping chamber 16 by natural flow down due to the difference in level of the molten metal by changing the state of the molten metal communication channel 5 from the closed state, where the molten metal communication channel 5 is closed by the regulation part 4 to shut off the transfer of the molten metal MM, to the open state, where the molten metal communication channel 5 is opened by the regulation part 4 to allow the transfer of the molten metal MM; and transferring, similarly with the transfer of the molten metal MM allowed, the molten metal MM in the molten metal holding chamber 13 into the tapping chamber 16 by the pressure of the gas supplied through the pressurizing part 13A.

[0107] When the level of the molten metal MM in the molten metal holding chamber 13 is higher than the level of the molten metal MM in the tapping chamber 16, it is preferred that the molten metal MM in the molten metal holding chamber 13 is transferred into the tapping chamber 16 by natural flow down due to the difference in level of the molten metal MM between the molten metal holding chamber 13 and the tapping chamber 16. The molten metal MM in the molten metal holding chamber 13 may be transferred into the tapping chamber 16 by the pressure of the gas supplied through the pressurizing part 13A, but use of the pressurizing part 13A incurs cost, such as for electric power for the operation.

[0108] On the other hand, when the level of the molten metal MM in the molten metal holding chamber 13 is lower than or the same as the level of the molten metal MM in the tapping chamber 16, even if the transfer of the molten metal MM is allowed by the regulation part 4, the transfer of the molten metal MM from the molten metal holding chamber 13 into the tapping chamber 16 by natural flow down will not occur. In this case, the molten metal MM in the molten metal holding chamber 13 may forcibly be transferred into the tapping chamber 16 by the pressure of the gas supplied through the pressurizing part 13A of the molten metal holding chamber 13.

[0109] When the molten metal MM is being transferred from the molten metal holding chamber 13 into the tapping chamber 15 by natural flow down, this pressure allows transfer of an additional amount of the molten metal MM, so that a larger amount of molten metal MM may be transferred to the tapping chamber 16 without wasting anything, and tapping of a larger amount of molten metal MM may be realized.

[0110] When the pressurizing part 13A is used, the gas to be supplied into the molten metal holding chamber 13 may be dry air or inert gas (nitrogen gas, argon gas, or the like). When the gas is supplied under pressure, the molten metal holding chamber 13 is completely sealed with the upper lid 13C of the molten metal holding chamber and the lid 13B of the molten metal supply port. Though not shown, dry air or inert gas (nitrogen gas, argon gas, or the like) compressed and pressurized using a compressor is adjusted to a predetermined pressure with a pressure reducing valve, which is confirmed using a pressure gauge, and the adjusted dry air or inert gas (nitrogen gas, argon gas, or the like) is sent into the molten metal holding chamber 13 via the pressurizing part 13A.

[0111] Discussion is now made with regard to the case where the molten metal MM in the molten metal holding chamber 13 is transferred into the tapping chamber 16 by the natural flow down due to the difference in level of the molten metal MM between the molten metal holding chamber 13 and the tapping chamber 16.

[0112] As discussed above, when the level of the molten metal MM in the molten metal holding chamber 13 is higher than the level of the molten metal MM in the tapping chamber 16, with this difference in level of the molten metal, by changing the state of the molten metal communication channel 5 from the closed state, where the molten metal communication channel 5 is closed by the regulation part 4 to shut off the transfer of the molten metal MM, to the open state, where the molten metal communication channel 5 is opened by the regulation part 4 to allow the transfer of the molten metal MM, the molten metal MM in the molten metal holding chamber 13 is transferred into the tapping chamber 16 by natural flow down due to the difference in level of the molten metal MM between the molten metal holding chamber 13 and the tapping chamber 16.

[0113] While the transfer of the molten metal MM in the molten metal holding chamber 13 into the tapping chamber 16 proceeds and when, for example, the surface of the molten metal MM is brought into contact with the lower end of the melt level sensor 16E, the molten metal communication channel 5 is closed by the regulation part 4 provided thereto to shut off the transfer of the molten metal MM, to thereby stop the transfer of the molten metal MM through the molten metal communication channel 5 into the tapping chamber 16. Upon stopping the transfer, for example, the level of the molten metal MM in the molten metal holding chamber 13 may still be higher than the level of the molten metal MM in the tapping chamber 16, as shown in FIG. 2. Then, as shown in FIG. 3, the molten metal communication channel 5 may be closed by the regulation part 4 to shut off the transfer of the molten metal MM.

[0114] According to the embodiment, the method of the present embodiment includes the step of tapping, with the transfer of the molten metal MM shut off by the regulation part 4, the molten metal MM in the tapping chamber 16 through the tapping channel 3 (e.g., interior of the tapping pipe 6) into a target place (e.g., interior of a sleeve of a die-casting machine) by the pressure of the gas supplied through the gas supply part 16A. For tapping the molten metal MM, the gas to be taken into the tapping chamber 16 via the gas supply part 16A is not particularly limited, but may preferably be dry air or inert gas (nitrogen gas, argon gas, or the like), which hardly affects the quality of the molten metal MM.

[0115] As the gas is supplied under pressure, the tapping may be carried out with the tapping chamber 16 completely sealed with the tapping chamber lid 16C, which allows tapping in a required amount without causing oxidation.

[0116] According to an embodiment, the gas supply part 16A may be equipped with a pressure gauge for pressurization and a velocimeter for measuring the supply rate of the gas. These instruments may be provided together with or separately from the gas supply part 16A.

[0117] The combination of the supply of the gas under pressure through the gas supply part 16A and the tapping channel 3 (e.g., tapping pipe 6) according to the embodiment, realizes precise tapping and tapping of a large amount of molten metal MM.

[0118] Though not shown, prior to the tapping, dry air or inert gas (nitrogen gas, argon gas, or the like) compressed and pressurized using a compressor is adjusted to a predetermined pressure with a pressure reducing valve, which is confirmed using a pressure gauge, and the adjusted dry air or inert gas (nitrogen gas, argon gas, or the like) is sent into the tapping chamber 16 via the gas supply part 16A.

[0119] Based on the data of various prior information input to the tapping furnace 1, such as information required for putting into practice stable tapping of a requisite amount of the molten metal MM per shot (by one tapping) confirmed in advance of actual operation, i.e., time lapsed from the start of detection of the molten metal MM reaching the outlet port 7 through the tapping channel 3 (e.g., interior channel of the tapping pipe 6) until tapping of a requisite amount, the pressure, speed, duration of supply, or the like of the gas supplied into the tapping chamber 16, configuration (inner diameter, length, size of the inlet port 9, or the like) of the tapping channel 3 (e.g., tapping pipe 6), and the number of the tapping channels 3 (e.g., tapping pipes 6) in the tapping chamber 16, the pressurizing/depressurizing is controlled via a control panel of the tapping furnace 1 during the actual operation to realize precise tapping.

[0120] In the embodiment of tapping according to the present invention, tapping of the molten metal MM in the tapping chamber 16 is started with the surface of the molten metal MM in contact with the lower end of the melt level sensor 16E. In other words, tapping of the molten metal MM is started with the surface of the molten metal MM in the tapping chamber 16 being at a constant level (also referred to as a constant melt level). In this way, the gas may always be supplied through the gas supply part 16A at a constant pressure, which facilitates control of the operation. Further, the tapping chamber 16 may be made smaller, which can also reduce the amount of the gas supplied through the gas supply part 16A for applying the pressure. The tapping chamber may be made smaller compared to conventional tapping chambers. In a downsized tapping chamber, gas with a lower pressurizing force may suffice for the tapping, so that the cost of the power required for the tapping may be reduced. FIG. 4 shows the state immediately after the tapping of the molten metal MM.

[0121] After the step of tapping the molten metal MM, the pressure in the tapping chamber 16 is returned to the atmospheric pressure by depressurizing through exhausting via the gas supply part 16A. The gas supply part 16A may be used not only for applying pressure, but also for reducing pressure. After the tapping step, the level of the molten metal MM in the molten metal holding chamber 13 may still be higher than the level of the molten metal MM in the tapping chamber 16 as shown, for example, in FIG. 4.

[0122] In this case, similarly to the series of flows as shown in FIGS. 1 to 4 discussed above, one cycle of or a plurality of cycles of transferring the molten metal MM in the molten metal holding chamber 13 into the tapping chamber 16 by natural flow down, and tapping the molten metal MM in the tapping chamber 16 through the tapping channel 3 (e.g., interior of the tapping pipe 6) into a target place (e.g., interior of a sleeve of a die-casting machine) by the pressure of the gas supplied through the gas supply part 16A, are carried out or repeated, as shown in FIGS. 5 to 7.

[0123] By repeating the plurality of the cycles, the amount of the molten metal MM in the molten metal holding chamber 13 gradually decreases. As mentioned above, the lower end of the melt level sensor 13E is set at the same level as the lower end of the melt level sensor 16E in the tapping chamber 16. This is for alerting timing for supplying the molten metal MM from outside the tapping furnace 1 into the molten metal holding chamber 13, when the transfer of the molten metal MM from the molten metal holding chamber 13 into the tapping chamber 16 only by natural flow down is becoming harder and finally the molten metal surface is disengaged from the lower end of the melt level sensor 13E (i.e., when the molten metal MM can no longer be transferred by natural flow down from the molten metal holding chamber 13 into the tapping chamber 16).

[0124] When the timing for supplying the molten metal is reached, the lid 13B of the molten metal supply port 13B is opened, and the molten metal MM is supplied through the port.

[0125] For the transfer of the molten metal MM from the molten metal holding chamber 13 into the tapping chamber 16 only by natural flow down according to the first embodiment, the lower end of the melt level sensor 13E (referred to as the lower limit 1) is positioned so that the molten metal heating units 2 are not exposed on the surface of the molten metal MM in the molten metal holding chamber 13 and not operated without molten metal therearound, and also so that the molten metal MM in the molten metal holding chamber 13 may forcibly be transferred into the tapping chamber 16 by pressurizing the interior of the molten metal holding chamber 13 with dry air or inert gas (nitrogen gas, argon gas, or the like) supplied through the pressurizing part 13A. Irrespective of this, the timing for supplying molten metal is reached, which may require frequent supply of molten metal.

[0126] In view of this, as shown in FIG. 8, the molten metal holding chamber 13 is provided with another melt level sensor 13G, aside from the melt level sensor 13E. The melt level sensor 13G extends down to immediately above the level of the molten metal heating units 2 but, for example, below the lower limit 1, and the lower limit level of the molten metal is set in advance, below which the molten metal heating units 2 are exposed on the surface of the molten metal MM in the molten metal holding chamber 13 and operated without molten metal therearound, if the molten metal MM in the molten metal holding chamber 13 may forcibly be transferred into the tapping chamber 16 by pressurizing the interior of the molten metal holding chamber 13 with dry air or inert gas (nitrogen gas, argon gas, or the like) supplied through the pressurizing part 13A, and the lower end of the melt level sensor 13G (referred to as lower limit 2) is matched to this lower limit level. With this arrangement, by setting the alert for the timing for supplying the molten metal MM from outside the tapping furnace 1 into the molten metal holding chamber 13 not at the lower limit 1, but at the lower limit 2, the molten metal MM may efficiently be transferred from the molten metal holding chamber 13 into the tapping chamber 16, and the timing for supplying the molten metal MM from outside the tapping furnace 1 into the molten metal holding chamber 13 may be decided on, which eliminates the need for frequent supply of the molten metal. This embodiment is referred to as a modification to the first embodiment.

[0127] According to this modified embodiment, the pressurizing part 13A is activated when the surface of the molten metal MM in the molten metal holding chamber 13 is disengaged from the lower limit 1 (i.e., when the molten metal MM can no longer be transferred by natural flow down from the molten metal holding chamber 13 into the tapping chamber 16), and the molten metal MM in the molten metal holding chamber 13 is forcibly transferred into the tapping chamber 16 by pressurizing the interior of the molten metal holding chamber 13 with dry air or inert gas (nitrogen gas, argon gas, or the like) supplied through the pressurizing part 13A. While the transfer of the molten metal proceeds and when the surface of the molten metal MM is brought into contact with the lower end of the melt level sensor 16E, the supply of the gas under pressure through the pressurizing part 13A is stopped, and the molten metal communication channel 5 is closed by the regulation part 4 provided thereto to shut off the transfer of the molten metal MM, to thereby stop the transfer of the molten metal MM through the molten metal communication channel 5 into the tapping chamber 16. After that, the pressure in the molten metal holding chamber 13 is returned to the atmospheric pressure by depressurizing through exhausting via the pressurizing part 13A. The pressurizing part 13A may be used not only for applying pressure, but also for reducing pressure. For activating the pressurizing part 13A, the molten metal holding chamber 13 is completely sealed with the upper lid 13C of the molten metal holding chamber and the lid 13B of the molten metal supply port.

[0128] Similarly to the above, the step of tapping, with the transfer of the molten metal MM shut off by the regulation part 4, the molten metal MM in the tapping chamber 16 through the tapping channel 3 (e.g., interior of the tapping pipe 6) into a target place (e.g., interior of a sleeve of a die-casting machine) by the pressure of the gas supplied through the gas supply part 16A is carried out, and then the pressure in the tapping chamber 16 is returned to the atmospheric pressure by depressurizing through exhausting via the gas supply part 16A. Further similarly to the above, after the state of the molten metal communication channel 5 from the shut off state, where the transfer of the molten metal MM is shut off by the regulation part 4, to the allowed state, where the transfer of the molten metal MM is allowed by the regulation part 4, one cycle of or a plurality of cycles of the following steps are carried out. One cycle of the steps includes activating the pressurizing part 13A, forcibly transferring the molten metal MM in the molten metal holding chamber 13 into the tapping chamber 16 by pressuring the interior of the molten metal holding chamber 13 through the pressurizing part 13A, and tapping the molten metal MM in the tapping chamber 16 through the tapping channel 3 (e.g., interior of the tapping pipe 6) into a target place (e.g., interior of a sleeve of a die-casting machine) by the pressure of the gas supplied through the gas supply part 16A. Then, when the surface of the molten metal is disengaged from the lower end of the melt level sensor 13G (lower limit 2) (i.e., the molten metal level reaches the limit, below which the molten metal heating units 2 are exposed on the surface of the molten metal MM in the molten metal holding chamber 13 and operated without molten metal therearound), the timing for supplying the molten metal MM from outside the tapping furnace 1 into the molten metal holding chamber 13 is alerted, and the molten metal MM is supplied.

[0129] In other words, when the level of the molten metal MM in the molten metal holding chamber 13 is higher than the level of the molten metal MM in the tapping chamber 16, the molten metal MM in the molten metal holding chamber 13 is transferred into the tapping chamber 16 by natural flow down due to the difference in level of the molten metal MM, and when the level of the molten metal MM in the molten metal holding chamber 13 is the same as the level of the molten metal MM in the tapping chamber 16 (i.e., when the molten metal MM can no longer be transferred by natural flow down from the molten metal holding chamber 13 into the tapping chamber 16), the molten metal MM in the molten metal holding chamber 13 may forcibly be transferred into the tapping chamber 16 by the pressure of the gas supplied through the pressurizing part 13A.

[0130] As may be understood from the above discussion, the pressurizing part 13A is not necessarily required for the transfer of the molten metal MM from the molten metal holding chamber 13 into the tapping chamber 16 by natural flow down and, when the pressurizing part 13A is provided, the molten metal holding chamber 13 is kept from intrusion of outside air. Accordingly, the compression part 13A as shown in FIGS. 1 to 7 is made to be kept from intrusion of the air outside the molten metal holding chamber 13.

[0131] It may be conceivable to initially set the lower end of the melt level sensor 13E to the lower limit 2, but for transferring the molten metal MM from the molten metal holding chamber 13 to the tapping chamber 16 by the natural flow down due to the difference in level of the molten metal MM between the molten metal holding chamber 13 and the tapping chamber 16, the lower end of the melt level sensor 16E of the tapping chamber 16 is set to the same level as the lower end of the melt level sensor 13E, which requires the tapping chamber 16 per se to be positioned at a lower level compared to the molten metal holding chamber 13, possibly resulting in disadvantageous distortion of the shape of the overall tapping furnace 1.

[0132] According to the modified embodiment, based on the data of information confirmed in advance of actual operation and input to the tapping furnace 1, such as information about the operation from disengagement of the surface of the molten metal MM in the molten metal holding chamber 13 from the lower limit 1 (i.e., when the molten metal MM can no longer be transferred by natural flow down from the molten metal holding chamber 13 into the tapping chamber 16), through activating the pressurizing part 13A and forcibly transferring the molten metal MM in the molten metal holding chambre 13 into the tapping chamber 16 by pressurizing the interior of the molten metal holding chamber 13 through the pressurizing part 13A, until the surface of the molten metal MM is brought into contact with the lower end of the melt level sensor 16E; information about the subsequent one or a plurality of cycles of activating the pressurizing part 13A again, and forcibly transferring the molten metal MM in the molten metal holding chambre 13 into the tapping chamber 16 by pressurizing the interior of the molten metal holding chamber 13 through the pressurizing part 13A, until the surface of the molten metal MM is brought into contact with the lower end of the melt level sensor 16E; and information that activating the pressurizing part 13A and forcibly transferring the molten metal MM in the molten metal holding chambre 13 into the tapping chamber 16 by pressurizing the interior of the molten metal holding chamber 13 by the pressurizing part 13A results in disengagement of the surface of the molten metal MM from the lower end of the melt level sensor 13G (lower limit 2), that is, various prior information including the number of times and the time lapsed from the activation of the pressurizing part 13A until the surface of the molten metal MM is brought into contact with the lower end of the melt level sensor 16E, the pressure, speed, duration of supply, or the like of the gas supplied into the molten metal holding chamber 13, and configuration (inner diameter, length, or the like) of the molten metal communication channel 5, the pressurizing/depressurizing is controlled via a control panel of the tapping furnace 1 during the actual operation to realize precise supply under pressure.

Second Embodiment

[0133] The second embodiment of the tapping furnace 1 according to the present invention is shown in FIGS. 9 to 15. Explanations of the same members and parts as in the first embodiment are omitted. According to the second embodiment, the molten metal holding chamber 13 is provided with the pressurizing part 13A, and the molten metal MM in the molten metal holding chamber 13 is transferred into the tapping chamber 16 simply by supplying dry air or inert gas (nitrogen gas, argon gas, or the like) through this pressurizing part 13A. In this way, irrespective of the level of the molten metal MM in the molten metal holding chamber 13 being higher, the same, or lower than the level of the molten metal MM in the tapping chamber 16, i.e., irrespective of the difference in level, the molten metal MM may be transferred.

[0134] For example, suppose the level of the molten metal MM in the molten metal holding chamber 13 is higher than the level of the molten metal MM in the tapping chamber 16, as shown in FIG. 9.

[0135] Then, from this state, with the transfer of the molten metal MM allowed by the regulation part 4, the molten metal MM in the molten metal holding chamber 13 is transferred to the tapping chamber 16 by the pressure of the gas supplied through the pressurizing part 13A.

[0136] While the transfer of the molten metal MM in the molten metal holding chamber 13 into the tapping chamber 16 proceeds and when, for example, the surface of the molten metal MM is brought into contact with the lower end of the melt level sensor 16E as shown in FIG. 10, the supply of the gas under pressure through the pressurizing part 13A is stopped, and the molten metal communication channel 5 is closed by the regulation part 4 provided thereto as shown in FIG. 11, to shut off the transfer of the molten metal MM, to thereby stop the transfer of the molten metal MM through the molten metal communication channel 5 into the tapping chamber 16. After that, the pressure in the molten metal holding chamber 13 is returned to the atmospheric pressure by depressurizing through exhausting via the pressurizing part 13A. The pressurizing part 13A may be used not only for applying pressure, but also for reducing pressure. For activating the pressurizing part 13A, the molten metal holding chamber 13 is completely sealed with the upper lid 13C of the molten metal holding chamber and the lid 13B of a molten metal supply port.

[0137] According to the embodiment, the method of the present embodiment includes the step of tapping, with the transfer of the molten metal MM shut off by the regulation part 4 as shown in FIG. 12, the molten metal MM in the tapping chamber 16 through the tapping channel 3 (e.g., interior of the tapping pipe 6) into a target place (e.g., interior of a sleeve of a die-casting machine) by the pressure of the gas supplied through the gas supply part 16A. As the gas is supplied under pressure, the tapping may be carried out with the tapping chamber 16 completely sealed with the tapping chamber lid 16C, which allows tapping in a required amount without causing oxidation.

[0138] Then, similarly to the series of flows as shown in FIGS. 9 to 12 discussed above, one cycle of or a plurality of cycles of transferring the molten metal MM in the molten metal holding chamber 13 into the tapping chamber 16 by pressurizing the interior of the molten metal holding chamber 13 via the pressurizing part 13A, and tapping the molten metal MM in the tapping chamber 16 through the interior of the tapping channel 3 (e.g., tapping pipe 6) into a target place (e.g., interior of a sleeve of a die-casting machine) by the pressure of the gas supplied through the gas supply part 16A are carried out or repeated, as shown in FIGS. 13 to 15.

[0139] By repeating the plurality of the cycles, the amount of the molten metal MM in the molten metal holding chamber 13 gradually decreases.

[0140] According to the second embodiment, the melt level sensor 13E of the first embodiment is replaced with a melt level sensor 13G. The melt level sensor 13G extends down to immediately above the level of the molten metal heaters 2 but, for example, below the level of the lower end of the melt level sensor 16E in the tapping chamber 16, and the lower limit level of the molten metal is set in advance, below which the molten metal heating units 2 are exposed on the surface of the molten metal MM in the molten metal holding chamber 13 and operated without molten metal therearound, if the molten metal MM in the molten metal holding chamber 13 may forcibly be transferred into the tapping chamber 16 by pressurizing the interior of the molten metal holding chamber 13 with dry air or inert gas (nitrogen gas, argon gas, or the like) supplied through the pressurizing part 13A, and the lower end of the melt level sensor 13G (referred to as lower limit 2) is matched to this lower limit level. With this arrangement, by setting the alert for the timing for supplying the molten metal MM from outside the tapping furnace 1 into the molten metal holding chamber 13 at the lower limit 2, the molten metal MM may efficiently be transferred from the molten metal holding chamber 13 into the tapping chamber 16, and the timing for supplying the molten metal MM from outside the tapping furnace 1 into the molten metal holding chamber 13 may be decided on, which eliminates the need for frequent supply of the molten metal.

[0141] Then, as discussed above, the one cycle or the plurality of the cycles are carried out or repeated and, when the surface of the molten metal is disengaged from the lower end of the melt level sensor 13G (lower limit 2) (i.e., the molten metal level reaches the limit, below which the molten metal heating units 2 are exposed on the surface of the molten metal MM in the molten metal holding chamber 13 and operated without molten metal therearound), the timing for supplying the molten metal MM from outside the tapping furnace 1 into the molten metal holding chamber 13 is alerted, and the molten metal MM is supplied.

[0142] According to the second embodiment, like the first embodiment, based on the data of various prior information confirmed in advance of actual operation and input to the tapping furnace 1, the pressurizing/depressurizing is controlled via a control panel of the tapping furnace 1 during the actual operation to realize precise supply under pressure.

Third Embodiment

[0143] The third embodiment of the tapping furnace 1 according to the present invention is shown in FIGS. 16 to 23.

[0144] FIG. 16 shows that the lower end of the melt level sensor 13E is positioned at the same level as the lower end of the melt level sensor 16E of the tapping chamber 16. This is for alerting timing for supplying the molten metal MM from outside the tapping furnace 1 into the molten metal holding chamber 13, when the amount of the molten metal in the molten metal holding chamber 13 decreases gradually while the transfer from the molten metal holding chamber 13 into the tapping chamber 16 and the tapping from the tapping chamber 16 of the molten metal MM are repeated by natural flow down due to the difference in level of the molten metal MM between the molten metal holding chamber 13 and the tapping chamber 16, and the transfer of the molten metal MM from the molten metal holding chamber 13 into the tapping chamber 16 by natural flow down is becoming harder, and finally the molten metal surface is disengaged from the lower end of the melt level sensor 13E (i.e., when the molten metal MM can no longer be transferred by natural flow down from the molten metal holding chamber 13 into the tapping chamber 16).

[0145] When the timing for supplying the molten metal is reached, the lid 13B of the molten metal supply port is opened, and the molten metal MM is supplied through the port. In order to detect the upper limit of the molten metal to be supplied, another melt level sensor 13F may be installed in addition to the melt level sensor 13E for detecting the lower limit of the amount of the molten metal.

[0146] The tapping chamber 16 may be provided with a gas supply/exhaust part 16G, through which the gas in the tapping chamber 16 may be exhausted to bring the tapping chamber 16 into a reduced pressure state.

[0147] In other words, with the molten metal communication channel 5 opened by the regulation part 4, by depressurizing inside the tapping chamber 16, the molten metal MM may efficiently be transferred from the molten metal holding chamber 13 via the molten metal communication channel 5 into the tapping chamber 16 until the melt level sensor 16E of the tapping chamber 16 detects the molten metal MM. The details will be discussed later.

[0148] According to the third embodiment, FIG. 16 indicates the relationship in molten metal surface, wherein the level of the molten metal MM in the molten metal holding chamber 13 is higher than the level of the molten metal MM in the tapping chamber 16. With this difference in level of the molten metal, the method of the present invention includes a transferring step of at least either of: transferring the molten metal MM in the molten metal holding chamber 13 into the tapping chamber 16 by natural flow down due to difference in level of the molten metal by changing the state of the molten metal communication channel 5 from the closed state, where the molten metal communication channel 5 is closed by the regulation part 4 to shut off the transfer of the molten metal MM, to the open state, where the molten metal communication channel 5 is opened by the regulation part 4 to allow the transfer of the molten metal MM; and transferring, similarly with the transfer of the molten metal MM allowed, the molten metal MM in the molten metal holding chamber 13 into the tapping chamber 16 by exhausting the gas through the gas supply/exhaust part 16G.

[0149] When the level of the molten metal MM in the molten metal holding chamber 13 is higher than the level of the molten metal MM in the tapping chamber 16, it is preferred that the molten metal MM in the molten metal holding chamber 13 is transferred into the tapping chamber 16 by natural flow down due to the difference in level of the molten metal MM between the molten metal holding chamber 13 and the tapping chamber 16. The molten metal MM in the molten metal holding chamber 13 may be transferred into the tapping chamber 16 by exhausting the gas from and thus depressurizing the tapping chamber 16 through the gas supply/exhaust part 16G, but use of the gas supply/exhaust part 16G incurs cost, such as for electric power for the operation. Note that the tapping chamber 16 is completely sealed with the tapping chamber lid 16C for depressurizing by exhausting gas or for pressuring by supplying gas as will be discussed later, through the gas supply/exhaust part 16G.

[0150] On the other hand, when the level of the molten metal MM in the molten metal holding chamber 13 is lower than or the same as the level of the molten metal MM in the tapping chamber 16, even if the transfer of the molten metal MM is allowed by the regulation part 4, the transfer of the molten metal MM from the molten metal holding chamber 13 into the tapping chamber 16 by natural flow down will not occur. In this case, the molten metal MM in the molten metal holding chamber 13 may forcibly be transferred into the tapping chamber 16 by exhausting the gas from and thus depressurizing the tapping chamber 16 through the gas supply/exhaust part 16G.

[0151] When the molten metal MM is being transferred from the molten metal holding chamber 13 into the tapping chamber 15 by natural flow down, this depressurizing allows transfer of an additional amount of the molten metal MM, so that a larger amount of molten metal MM may be transferred to the tapping chamber 16 without wasting anything, and tapping of a larger amount of molten metal MM may be realized.

[0152] Discussion is now made with regard to the case where the molten metal MM in the molten metal holding chamber 13 is transferred into the tapping chamber 16 by natural flow down due to the difference in level of the molten metal MM between the molten metal holding chamber 13 and the tapping chamber 16.

[0153] As discussed above, when the level of the molten metal MM in the molten metal holding chamber 13 is higher than the level of the molten metal MM in the tapping chamber 16, with this difference in level of the molten metal, by changing the state of the molten metal communication channel 5 from the closed state, where the molten metal communication channel 5 is closed by the regulation part 4 to shut off the transfer of the molten metal MM, to the open state, where the molten metal communication channel 5 is opened by the regulation part 4 to allow the transfer of the molten metal MM, the molten metal MM in the molten metal holding chamber 13 is transferred into the tapping chamber 16 by natural flow down due to the difference in level of the molten metal MM between the molten metal holding chamber 13 and the tapping chamber 16.

[0154] While the transfer of the molten metal MM in the molten metal holding chamber 13 into the tapping chamber 16 proceeds and when, for example, the surface of the molten metal MM is brought into contact with the lower end of the melt level sensor 16E, the molten metal communication channel 5 is closed by the regulation part 4 provided thereto to shut off the transfer of the molten metal MM, to thereby stop the transfer of the molten metal MM through the molten metal communication channel 5 into the tapping chamber 16. Upon stopping the transfer, for example, the level of the molten metal MM in the molten metal holding chamber 13 may still be higher than the level of the molten metal MM in the tapping chamber 16, as shown in FIG. 17. Then, as shown in FIG. 18, the molten metal communication channel 5 may be closed by the regulation part 4 to shut off the transfer of the molten metal MM.

[0155] According to the embodiment, the method of the present embodiment includes the step of tapping, with the transfer of the molten metal MM shut off by the regulation part 4, the molten metal MM in the tapping chamber 16 through the interior of the tapping channel 3 (e.g., tapping pipe 6) into a target place (e.g., interior of a sleeve of a die-casting machine) by the pressure of the gas supplied through the gas supply/exhaust part 16G. For tapping the molten metal MM, the gas to be taken into the tapping chamber 16 via the gas supply/exhaust part 16G is not particularly limited, but may preferably be dry air or inert gas (nitrogen gas, argon gas, or the like), which hardly affects the quality of the molten metal MM.

[0156] As discussed above, the tapping chamber 16 is completely sealed with the tapping chamber lid 16C, which allows tapping in a required amount without causing oxidation.

[0157] According to the embodiment, the gas supply/exhaust part 16G may be equipped with a pressure gauge for pressurization and depressurization, and a velocimeter for measuring the supply rate and exhaust rate of the gas. These instruments may be provided together with or separately from the gas supply/exhaust part 16G.

[0158] The combination of the supply of the gas under pressure through the gas supply/exhaust part 16G and the tapping channel 3 (e.g., tapping pipe 6) according to the embodiment, realizes precise tapping and tapping of a large amount of molten metal MM.

[0159] Though not shown, prior to the tapping, dry air or inert gas (nitrogen gas, argon gas, or the like) compressed and pressurized using a compressor is adjusted to a predetermined pressure with a pressure reducing valve, which is confirmed using a pressure gauge, and the adjusted dry air or inert gas (nitrogen gas, argon gas, or the like) is sent into the tapping chamber 16 via the gas supply/exhaust part 16G.

[0160] Based on the data of various prior information input to the tapping furnace 1, such as information required for putting into practice stable tapping of a requisite amount of the molten metal MM per shot (by one tapping) confirmed in advance of actual operation, i.e., time lapsed from the start of detection of the molten metal MM reaching the outlet port 7 through the interior channel of the tapping channel 3 (e.g., tapping pipe 6) until tapping of a requisite amount, the pressure, speed, duration of supply, or the like of the gas supplied into the tapping chamber 16, configuration (inner diameter, length, size of the inlet port 9, or the like) of the tapping channel 3 (e.g., tapping pipe 6), and the number of the tapping channels 3 (e.g., tapping pipes 6) in the tapping chamber 16, the pressurizing/depressurizing is controlled via a control panel of the tapping furnace 1 during the actual operation to realize precise tapping.

[0161] In the embodiment of tapping according to the present invention, tapping of the molten metal MM in the tapping chamber 16 is started with the surface of the molten metal MM in contact with the lower end of the melt level sensor 16E. In other words, tapping of molten metal is started with the surface of the molten metal MM in the tapping chamber 16 being at a predetermined level (also referred to as a constant melt level). In this way, the gas may always be supplied through the gas supply/exhaust part 16G at a constant pressure, which facilitates control of the operation. Further, the tapping chamber 16 may be made smaller, which can also reduce the amount of the gas supplied through the gas supply/exhaust part 16G for applying the pressure. The tapping chamber may be made smaller compared to conventional tapping chambers.

[0162] In a downsized tapping chamber, gas with a lower pressurizing force may suffice for the tapping, so that the cost of the power required for the tapping may be reduced.

[0163] After the tapping step, the pressure in the tapping chamber 16 is returned to the atmospheric pressure by depressurizing through exhausting via the gas supply/exhaust part 16G. The gas supply/exhaust part 16G may be used not only for applying pressure, but also for reducing pressure. After the tapping step, the level of the molten metal MM in the molten metal holding chamber 13 may still be higher than the level of the molten metal MM in the tapping chamber 16 as shown, for example, in FIG. 19.

[0164] In this case, similarly to the series of flows as shown in FIGS. 16 to 19 discussed above, one cycle of or a plurality of cycles of transferring the molten metal MM in the molten metal holding chamber 13 into the tapping chamber 16 by natural flow down, and tapping the molten metal MM in the tapping chamber 16 through the interior of the tapping channel 3 (e.g., tapping pipe 6) into a target place (e.g., interior of a sleeve of a die-casting machine) by the pressure of the gas supplied through the gas supply/exhaust part 16G, are carried out or repeated, as shown in FIGS. 20 to 22.

[0165] By repeating the plurality of the cycles, the amount of the molten metal MM in the molten metal holding chamber 13 gradually decreases. As mentioned above, the lower end of the melt level sensor 13E is set at the same level as the lower end of the melt level sensor 16E in the tapping chamber 16. This is for alerting timing for supplying the molten metal MM from outside the tapping furnace 1 into the molten metal holding chamber 13, when the transfer of the molten metal MM from the molten metal holding chamber 13 into the tapping chamber 16 only by natural flow down is becoming harder and finally the molten metal surface is disengaged from the lower end of the melt level sensor 13E (i.e., when the molten metal MM can no longer be transferred by natural flow down from the molten metal holding chamber 13 into the tapping chamber 16).

[0166] When the timing for supplying the molten metal is reached, the lid 13B of the molten metal supply port 13B is opened, and the molten metal MM is supplied through the port.

[0167] For the transfer of the molten metal MM from the molten metal holding chamber 13 into the tapping chamber 16 only by natural flow down according to the third embodiment, the lower end of the melt level sensor 13E (referred to as the lower limit 1) is positioned so that the molten metal heating units 2 are not exposed on the surface of the molten metal MM in the molten metal holding chamber 13 and not operated without molten metal therearound, and also so that the molten metal MM in the molten metal holding chamber 13 may forcibly be transferred into the tapping chamber 16 by exhausting the gas from and thus depressurizing the tapping chamber 16 through the gas supply/exhaust part 16G. Irrespective of this, the timing for supplying molten metal is reached, which may require frequent supply of molten metal.

[0168] In view of this, as shown in FIG. 23, the molten metal holding chamber 13 is provided with another melt level sensor 13G, aside from the melt level sensor 13E. The melt level sensor 13G extends down to immediately above the level of the molten metal heating units 2 but, for example, below the lower limit 1, and the lower limit level of the molten metal is set in advance, below which the molten metal heating units 2 are exposed on the surface of the molten metal MM in the molten metal holding chamber 13 and operated without molten metal therearound, if the molten metal MM in the molten metal holding chamber 13 may forcibly be transferred into the tapping chamber 16 by exhausting the gas from and thus depressurizing the tapping chamber 16 through the gas supply/exhaust part 16G, and the lower end of the melt level sensor 13G (referred to as lower limit 2) is matched to this lower limit level. With this arrangement, by setting the alert for the timing for supplying the molten metal MM from outside the tapping furnace 1 into the molten metal holding chamber 13 not at the lower limit 1, but at the lower limit 2, the molten metal MM may efficiently be transferred from the molten metal holding chamber 13 into the tapping chamber 16, and the timing for supplying the molten metal MM from outside the tapping furnace 1 into the molten metal holding chamber 13 may be decided on, which eliminates the need for frequent supply of the molten metal. This embodiment is referred to as a modification to the third embodiment.

[0169] According to this modified embodiment, the gas supply/exhaust part 16G is activated when the surface of the molten metal MM in the molten metal holding chamber 13 is disengaged from the lower limit 1 (i.e., when the molten metal MM can no longer be transferred by natural flow down from the molten metal holding chamber 13 into the tapping chamber 16), and the molten metal MM in the molten metal holding chamber 13 is forcibly transferred into the tapping chamber 16 by exhausting the gas from and thus depressurizing the tapping chamber 16 through the gas supply/exhaust part 16G. While the transfer of the molten metal proceeds and when the surface of the molten metal MM is brought into contact with the lower end of the melt level sensor 16E, the exhausting of the gas for depressurizing through the gas supply/exhaust part 16G is stopped, and the molten metal communication channel 5 is closed by the regulation part 4 provided thereto to shut off the transfer of the molten metal MM, to thereby stop the transfer of the molten metal MM through the molten metal communication channel 5 into the tapping chamber 16. After that, the pressure in the tapping chamber 16 is returned to the atmospheric pressure by pressurizing the interior of the tapping chamber 16 through supply of gas via the gas supply/exhaust part 16G. Or the transfer of the molten metal MM through the molten metal communication channel 5 into the tapping chamber 16 is kept stopped. For activating the gas supply/exhaust part 16G, the tapping chamber 16 is completely sealed with the tapping chamber lid 16C.

[0170] Then, through the step of tapping the molten metal MM in the tapping chamber 16 through the tapping channel 3 (e.g., tapping pipe 6) into a target place (e.g., interior of a sleeve of a die-casting machine) by the pressure of the gas supplied through the gas supply/exhaust part 16G, the pressure in the tapping chamber 16 is returned to the atmospheric pressure by depressurizing through exhausting via the gas supply/exhaust part 16G. Then, similarly to the above again, one cycle of or a plurality of cycles of the following steps is carried out. One cycle of the steps includes changing the state of the molten metal communication channel 5 from the shut off state, where the transfer of the molten metal MM is shut off by the regulation part 4, to the allowed state, where the transfer of the molten metal MM is allowed by the regulation part 4, activating the gas supply/exhaust part 16G again, forcibly transferring the molten metal MM in the molten metal holding chamber 13 into the tapping chamber 16 by depressurizing with the gas supply/exhaust part 16G, and tapping the molten metal MM in the tapping chamber 16 through the interior of the tapping channel 3 (e.g., tapping pipe 6) into a target place (e.g., interior of a sleeve of a die-casting machine) by the pressure of the gas supplied through the gas supply/exhaust part 16G. Then, when the surface of the molten metal is disengaged from the lower end of the melt level sensor 13G (lower limit 2) (i.e., the molten metal level reaches the limit, below which the molten metal heating units 2 are exposed on the surface of the molten metal MM in the molten metal holding chamber 13 and operated without molten metal therearound), the timing for supplying the molten metal MM from outside the tapping furnace 1 into the molten metal holding chamber 13 is alerted, and the molten metal MM is supplied.

[0171] In other words, when the level of the molten metal MM in the molten metal holding chamber 13 is higher than the level of the molten metal MM in the tapping chamber 16, the molten metal MM in the molten metal holding chamber 13 is transferred into the tapping chamber 16 by natural flow down due to the difference in level of the molten metal MM, and when the level of the molten metal MM in the molten metal holding chamber 13 is the same as the level of the molten metal MM in the tapping chamber 16 (i.e., when the molten metal MM can no longer be transferred by natural flow down from the molten metal holding chamber 13 into the tapping chamber 16), the molten metal MM in the molten metal holding chamber 13 may forcibly be transferred into the tapping chamber 16 by the depressurization with the gas exhausted through the gas supply/exhaust part 16G.

[0172] It may be conceivable to initially set the lower end of the melt level sensor 13E to the lower limit 2, but for transferring the molten metal MM from the molten metal holding chamber 13 to the tapping chamber 16 by the natural flow down due to the difference in level of the molten metal MM between the molten metal holding chamber 13 and the tapping chamber 16, the lower end of the melt level sensor 16E of the tapping chamber 16 is set to the same level as the lower end of the melt level sensor 13E, which requires the tapping chamber 16 per se to be positioned at a lower level compared to the molten metal holding chamber 13, possibly resulting in disadvantageous distortion of the shape of the overall tapping furnace 1.

[0173] According to the modified embodiment, based on the data of information confirmed in advance of actual operation and input to the tapping furnace 1, such as information about the operation from disengagement of the surface of the molten metal MM in the molten metal holding chamber 13 from the lower limit 1 (i.e., when the molten metal MM can no longer be transferred by natural flow down from the molten metal holding chamber 13 into the tapping chamber 16), through activating the gas supply/exhaust part 16G and forcibly transferring the molten metal MM in the molten metal holding chambre 13 into the tapping chamber 16 by exhausting the gas from and thus depressurizing the tapping chamber 16 through the gas supply/exhaust part 16G, until the surface of the molten metal MM is brought into contact with the lower end of the melt level sensor 16E; information about the subsequent one or a plurality of cycles of activating the gas supply/exhaust part 16G again, and forcibly transferring the molten metal MM in the molten metal holding chambre 13 into the tapping chamber 16 by exhausting the gas from and thus depressurizing the tapping chamber 16 through the gas supply/exhaust part 16G, until the surface of the molten metal MM is brought into contact with the lower end of the melt level sensor 16E; and information that activating the gas supply/exhaust part 16G and forcibly transferring the molten metal MM in the molten metal holding chambre 13 into the tapping chamber 16 by exhausting the gas from and thus depressurizing the tapping chamber 16 through the gas supply/exhaust part 16G, results in disengagement of the surface of the molten metal MM from the lower end of the melt level sensor 13G (lower limit 2) (i.e., the molten metal level reaches the limit, below which the molten metal heaters 2 are exposed on the surface of the molten metal MM in the molten metal holding chamber 13 and operated without molten metal therearound), that is, various prior information including the number of times and the time lapsed from the activation of the gas supply/exhaust part 16G until the surface of the molten metal MM is brought into contact with the lower end of the melt level sensor 16E, the pressure, speed, duration of supply, or the like of the gas supplied into the molten metal holding chamber 13, and configuration (inner diameter, length, or the like) of the molten metal communication channel 5, the pressurizing/depressurizing is controlled via a control panel of the tapping furnace 1 during the actual operation to realize precise supply under pressure.

Fourth Embodiment

[0174] The fourth embodiment of the tapping furnace 1 according to the present invention is shown in FIGS. 24 to 30. Explanations of the same members and parts as in the third embodiment are omitted. According to the fourth embodiment, the tapping chamber 16 is provided with the gas supply/exhaust part 16G, and the molten metal MM in the molten metal holding chamber 13 is transferred into the tapping chamber 16 only by exhausting the gas from and thus depressurizing the tapping chamber 16 through the air supply/exhaust part 16G. In this way, irrespective of the level of the molten metal MM in the molten metal holding chamber 13 being higher, the same, or lower than the level of the molten metal MM in the tapping chamber 16, i.e., irrespective of the difference in level, the molten metal MM may be transferred.

[0175] For example, suppose the level of the molten metal MM in the molten metal holding chamber 13 is higher than the level of the molten metal MM in the tapping chamber 16, as shown in FIG. 24.

[0176] Then, from this state, by allowing by the regulation part 4 the transfer of the molten metal MM, the molten metal MM in the molten metal holding chamber 13 is transferred to the tapping chamber 16 by exhausting the gas from and thus depressurizing the tapping chamber 16 through the gas supply/exhaust part 16G.

[0177] As shown in FIG. 25, while the transfer of the molten metal MM in the molten metal holding chamber 13 into the tapping chamber 16 proceeds and when, for example, the surface of the molten metal MM is brought into contact with the lower end of the melt level sensor 16E, the exhausting of the gas for depressurizing by the gas supply/exhaust part 16G is stopped, and as shown in FIG. 26, the molten metal communication channel 5 is closed by the regulation part 4 provided thereto to shut off the transfer of the molten metal MM, to thereby stop the transfer of the molten metal MM through the molten metal communication channel 5 into the tapping chamber 16. After that, the pressure in the tapping chamber 16 is returned to the atmospheric pressure by pressurizing the interior of the tapping chamber 16 through supply of gas via the gas supply/exhaust part 16G. Or the transfer of the molten metal MM through the molten metal communication channel 5 into the tapping chamber 16 is kept stopped. The tapping chamber 16 is completely sealed with the tapping chamber lid 16C.

[0178] According to the embodiment, the method of the present embodiment includes the step of tapping, with the transfer of the molten metal MM shut off by the regulation part 4, as shown in FIG. 27, the molten metal MM in the tapping chamber 16 through the interior of the tapping channel 3 (e.g., tapping pipe 6) into a target place (e.g., interior of a sleeve of a die-casting machine) by the pressure of the gas supplied through the gas supply/exhaust part 16G. As the gas is supplied under pressure, the tapping may be carried out with the tapping chamber 16 completely sealed with the tapping chamber lid 16C, which allows tapping in a required amount without causing oxidation.

[0179] The state of the molten metal MM is changed from the shut off state, where the transfer is shut off by the regulation part 4, to the allowed state, where the transfer is allowed by the regulation part 4, as shown in FIG. 28. Through the step of transferring the molten metal MM in the molten metal holding chamber 13 into the tapping chamber 16 by exhausting the gas from and thus depressurizing the tapping chamber 16 through the gas supply/exhaust part 16G in this state, the molten metal MM in the molten metal holding chamber 13 is transferred to the tapping chamber 16. While the transfer proceeds and when, for example, the surface of the molten metal MM is brought into contact with the lower end of the melt level sensor 16E, as shown in FIG. 29, the exhausting of the gas for depressurizing by the gas supply/exhaust part 16G is stopped, and the molten metal communication channel 5 is closed by the regulation part 4 provided thereto to shut off the transfer of the molten metal MM, to thereby stop the transfer of the molten metal MM through the molten metal communication channel 5 into the tapping chamber 16. After that, the pressure in the tapping chamber 16 is returned to the atmospheric pressure by pressurizing the interior of the tapping chamber 16 through supply of gas via the gas supply/exhaust part 16G. Or the transfer of the molten metal MM through the molten metal communication channel 5 into the tapping chamber 16 is kept stopped. With the transfer of the molten metal MM shut off by the regulation part 4, as shown in FIG. 30, the step of tapping the molten metal MM in the tapping chamber 16 through the interior of the tapping channel 3 (e.g., tapping pipe 6) into a target place (e.g., interior of a sleeve of a die-casting machine) by the pressure of the gas supplied through the gas supply/exhaust part 16G, is carried out.

[0180] Then, as discussed above, one cycle of or a plurality of cycles of transferring the molten metal MM in the molten metal holding chamber 13 into the tapping chamber 16 by depressurizing the tapping chamber 16 through the gas supply/exhaust part 16G, and tapping the molten metal MM in the tapping chamber 16 through the interior of the tapping channel 3 (e.g., tapping pipe 6) into a target place (e.g., interior of a sleeve of a die-casting machine) by the pressure of the gas supplied through the gas supply/exhaust part 16G, are carried out or repeated.

[0181] By repeating the plurality of the cycles, the amount of the molten metal MM in the molten metal holding chamber 13 gradually decreases.

[0182] According to the fourth embodiment, the melt level sensor 13E of the third embodiment is replaced with the melt level sensor 13G. The melt level sensor 13G extends down to immediately above the level of the molten metal heating units 2 but, for example, below the level of the lower end of the melt level sensor 16E in the tapping chamber 16, and the lower limit level of the molten metal is set in advance, below which the molten metal heating units 2 are exposed on the surface of the molten metal MM in the molten metal holding chamber 13 and operated without molten metal therearound, if the molten metal MM in the molten metal holding chamber 13 may forcibly be transferred into the tapping chamber 16 by exhausting the gas from and thus depressurizing the tapping chamber 16 through the gas supply/exhaust part 16G, and the lower end of the melt level sensor 13G (referred to as lower limit 2) is matched to this lower limit level. With this arrangement, by setting the alert for the timing for supplying the molten metal MM from outside the tapping furnace 1 into the molten metal holding chamber 13 at the lower limit 2, the molten metal MM may efficiently be transferred from the molten metal holding chamber 13 into the tapping chamber 16, and the timing for supplying the molten metal MM from outside the tapping furnace 1 into the molten metal holding chamber 13 may be decided on, which eliminates the need for frequent supply of the molten metal.

[0183] Then, as discussed above, the one cycle or the plurality of the cycles are carried out or repeated and, when the surface of the molten metal is disengaged from the lower end of the melt level sensor 13G (lower limit 2) (i.e., the molten metal level reaches the limit, below which the molten metal heating units 2 are exposed on the surface of the molten metal MM in the molten metal holding chamber 13 and operated without molten metal therearound), the timing for supplying the molten metal MM from outside the tapping furnace 1 into the molten metal holding chamber 13 is alerted, and the molten metal MM is supplied.

[0184] According to the fourth embodiment, like the third embodiment, based on the bata of various prior information confirmed in advance of actual operation and input to the tapping furnace 1, the pressurizing/depressurizing is controlled via a control panel of the tapping furnace 1 during the actual operation to realize precise supply under pressure.

[0185] According to the embodiments, when a certain volume of the molten metal holding chamber 13 is ensured, the amount of the molten metal MM to be held in the molten metal holding chamber 13 may be increased. Alternatively, even with a small volume of the tapping chamber 16, by retaining in the tapping chamber 16 the amount of the molten metal MM by each transfer from the molten metal holding chamber 13 into the tapping chamber 16, the molten metal MM may precisely be tapped from the tapping chamber 16.

[0186] For, as conventionally, tapping the molten metal into a ladle, and then transferring the molten metal from the ladle into, for example, a cavity, if the ladle receives in one tapping the amount of the molten metal required for the cavity, a ladle of the size commensurate with the capacity of the cavity is required.

[0187] When a ladle of the size commensurate with the capacity of the cavity is used, the outlet port of the tapping chamber into the ladle should made large enough, which leads to increased facility cost of the tapping furnace, increased heat dissipation energy with the enlargement of the outlet port, and larger contact area between the molten metal and the air, resulting in increased oxidation.

[0188] The above-mentioned problem is significant, for example, in so-called giga-casting, in which a larger amount of molten metal is tapped in one tapping in casting facilities, such as a die-casting machine, with the expansion of production of electric vehicles (EV).

[0189] In contrast, the embodiments of the present invention does not have such an outlet port which causes the above problems. Further, according to the embodiments, when the amount of the molten metal required by the target place (e.g., for giga-casting) is large, a sufficient tapping amount by one shot (one tapping) may be secured by increasing the thickness of the tapping pipe 6, increasing the number of the tapping pipes 6, or the like manner, to thereby solve the above problem. Still further, according to the embodiments, a sufficient tapping amount by one shot (one tapping) may also be secured by means of retaining a large amount of molten metal MM in the tapping chamber 16 through transfer of the molten metal MM by, in addition to the transfer of the molten metal MM from the molten metal holding chamber 13 into the tapping chamber 16 by natural flow down, pressurizing the interior of the molten metal holding chamber 13 through the pressurizing part 13A, or depressurizing the tapping chamber 16 through the gas supply/exhaust part 16G, to thereby solve the above problem.

[0190] Further, the tapping furnace 1 according to the embodiments employs the tapping channel 3 (e.g., tapping pipe 6) in contrast to the conventional tapping, where a requisite amount of molten metal MM is ladled and moved out of the tapping furnace 1, so that the tapping furnace 1 is highly safe without the risk of spilling the molten metal MM during ladling, or injuring the workers with spilled molten metal MM. In embodiments wherein the tapping is effected by supplying gas under pressure, tapping from the tapping chamber 16 may be effected with the tapping chamber 16 completely sealed with the tapping chamber lid 16C, which allows tapping of a required amount without causing oxidation.

[0191] In the illustrated embodiments, the tapping channel 3 (e.g., tapping pipe 6) is provided penetrating a side wall of the tapping furnace 1, but the tapping channel 3 (e.g., tapping pipe 6) may alternatively be provided penetrating the tapping chamber lid 16C, as shown in FIG. 31. The tapping furnace 1 and the tapping channel 3 (e.g., tapping pipe 6) may integrally be formed. When the tapping furnace 1 and the tapping channel 3 (e.g., tapping pipe 6) are separately formed, only the tapping channel 3 (e.g., tapping pipe 6) may be exchanged when the time for replacement of the tapping channel 3 (e.g., tapping pipe 6) comes. In tapping the molten metal MM out of the tapping furnace 1, the space inside the tapping channel 3 (e.g., tapping pipe 6) where the molten metal MM passes, is the tapping channel 3.

[0192] The tapping channel 3 (e.g., tapping pipe 6) has an inlet port 9 for molten metal MM at one end immersed in the molten metal MM in the tapping chamber 16, and an outlet port 7 for molten metal MM at the other end for tapping the molten metal M out of the tapping furnace 1, where the tapping channel 3 penetrates a side wall or the tapping chamber lid 16C of the tapping furnace 1 from the interior side of the tapping chamber 16 and protrudes out of the tapping furnace 1. The tapping pipe 6 is not particularly limited, and may preferably be in the form of an elongate cylinder made of, for example, fine ceramics or ceramic-based aluminum titanate, for its strength and durability.

[0193] By pressurizing the interior of the tapping chamber 16 for a certain period of time with pressurized dry air or inert gas (nitrogen gas, argon gas, or the like) supplied through the gas supply part 16A or the gas supply/exhaust part 16G, the molten metal MM in the tapping chamber 16 may be pushed out through the tapping channel 3 (e.g., tapping pipe 6) and, accordingly, to the outside of the tapping furnace 1.

[0194] For keeping the temperature of the molten metal MM from lowering during tapping, it is preferred to dispose an auxiliary heater 8 on at least any of the portions of the tapping pipe 6 protruding through a side wall of the tapping furnace 1, protruding through the tapping chamber lid 16C, and protruding outside the tapping furnace 1.

[0195] The tapping channel 3 (e.g., tapping pipe 6) is provided with the inlet port 9 and the outlet port 7, and may also have one-way valve means provided therein.

[0196] By pressurizing the molten metal MM in the tapping chamber 16, the molten metal MM enters the tapping channel 3 (e.g., tapping pipe 6) through the inlet port 9, transfers through the tapping channel 3 (e.g., tapping pipe 6), and flows out of the outlet port 7 in a predetermined amount. With one-way valve means, when provided, flow of the molten metal MM into the tapping pipe 6 through the inlet port 9 is stopped when the pressurizing is stopped or the pressurizing force is lowered. As the one-way valve means functions to block the tapping channel 3 (e.g., tapping pipe 6), external air is kept from flowing into the tapping chamber 16 to avoid oxidation of the molten metal MM retained in the tapping chamber 16.

[0197] Beyond the outlet port 7 of the tapping pipe 6, the molten metal MM may be poured into a sleeve of a die-casting machine, or into a cavity of a mold for a product to be produced, attached to the outlet port 7.

<Molten Metal Communication Channel>

[0198] The molten metal holding chamber 13 and the tapping chamber 16 communicate with each other via the molten metal communication channel 5. The molten metal communication channel 5 is provided with the regulation part 4, which is capable of separating the molten metal holding chamber 13 and the tapping chamber 16, and opening/closing the molten metal communication channel 5, for example, by elevating/lowering. The regulation part 4 may be elevated/lowered manually, or may be configured such that, with the regulation part 4 elevated, the molten metal MM is flown from the molten metal holding chamber 13 into the tapping chamber 16 and, when the level of the molten metal rises until detected by the melt level sensor 16E, the regulation part 4 is automatically lowered to close the molten metal communication channel 5 so that the molten metal MM no longer flows into the tapping chamber 16.

[0199] FIG. 31 shows an embodiment which is provided, as the regulation part 4, with an elevating/lowering rotary shut-off valve 12 for opening/closing the molten metal communication channel 5. The elevating/lowering rotary shut-off valve 12 moves up and down and, with the valve 12 in the upper position, the molten metal communication channel 5 is opened, whereas with the valve 12 in the lower position, the molten metal communication channel 5 is blocked and closed. The elevating/lowering rotary shut-off valve 12 may be opened/closed manually, or may be configured such that, with the elevating/lowering rotary shut-off valve 12 elevated, the molten metal MM is flown into the tapping chamber 16 and, when the level of the molten metal rises until detected by the melt level sensor 16E, the elevating/lowering rotary shut-off valve 12 is automatically lowered to close the molten metal communication channel 5 so that the molten metal MM no longer flows into the tapping chamber 16. The regulation part 4 may be located in the part of the molten metal communication channel 5 closer to the molten metal holding chamber 13, in the part of the molten metal communication channel 5 closer to the tapping chamber 16, or in the middle of the molten metal communication channel 5, as long as the regulation part 4 can separate the molten metal holding chamber 13 and the tapping chamber 16.

[0200] According to the embodiment, the tapping furnace 1 may tap the molten metal MM repeatedly, so that tapping of a large amount of molten metal MM may be achieved.

<Control Section>

[0201] The tapping method discussed above is preferably performed by tapping apparatus having a control section 50 as shown in FIGS. 32 to 35.

[0202] The control section 50 is connected with each of the gas supply part 16A or gas supply/exhaust part 16G, the pressurizing part 13A, and the regulation part 4, for sending/receiving signals therebetween, and is also configured to receive signals from the melt level sensors 13E, 13F, 13G, and 16E.

[0203] The control section 50 may include a CPU, a memory, and a program for executing the tapping operation, which are not shown.

[0204] As indicated in FIGS. 32 and 33, the control section 50 functions to control at least either of transferring, with the transfer of the molten metal MM allowed by the regulation part 4, the molten metal MM in the molten metal holding chamber 13 into the tapping chamber 16 by natural flow down due to the difference in level of the molten metal MM between the molten metal holding chamber 13 and the tapping chamber 16, and transferring, with the transfer of the molten metal MM allowed by the regulation part 4, the molten metal MM in the molten metal holding chamber 13 into the tapping chamber 16 by the pressure of the gas supplied through the pressurizing part 13A which is capable of supplying gas from outside and into the molten metal holding chamber 13, and tapping, with the transfer of the molten metal MM shut off by the regulation part 4, the molten metal MM in the tapping chamber 16 though the interior of the tapping channel 3 into a target place by the pressure of the gas supplied through the gas supply part 16A.

[0205] As indicated in FIGS. 34 and 35, the control section 50 functions to control at least either of transferring, with the transfer of the molten metal MM allowed by the regulation part 4, the molten metal MM in the molten metal holding chamber 13 into the tapping chamber 16 by natural flow down due to the difference in level of the molten metal MM between the molten metal holding chamber 13 and the tapping chamber 16, and transferring, with the transfer of the molten metal MM allowed by the regulation part 4, the molten metal MM in the molten metal holding chamber 13 into the tapping chamber 16 by exhausting the gas through the gas supply/exhaust part 16G, and tapping, with the transfer of the molten metal MM shut off by the regulation part 4, the molten metal MM in the tapping chamber 16 though the interior of the tapping channel 3 into a target place by the gas supplied under pressure through the gas supply/exhaust part 16G.

INDUSTRIAL APPLICABILITY

[0206] The molten metal MM may be not only aluminum or aluminum alloys, but also other molten metals MM.

[0207] The technical scope of the present invention is not limited to the embodiments of the invention as discussed above, and various modifications may be made to the embodiments without departing from the gist of the present invention. For example, the tapping furnace 1 of the present invention may be applied to a metal melting furnace, a molten-metal tapping furnace, a melting furnace, a holding furnace, a low-pressure casting furnace, or the like.

DESCRIPTION OF REFERENCE SIGNS

[0208] 1: tapping furnace [0209] 2: molten metal heating unit [0210] 3: tapping channel [0211] 4: regulation part [0212] 5: molten metal communication channel [0213] 6: tapping pipe [0214] 7: outlet port [0215] 8: auxiliary heater [0216] 9: inlet port [0217] 13: molten metal holding chamber [0218] 13A: pressurizing part [0219] 13B: lid of molten metal supply port [0220] 13C: upper lid of molten metal holding chamber [0221] 13D: molten metal holding chamber vessel [0222] 13E: melt level sensor (for detecting lower limit level of molten metal in molten metal holding chamber for transferring molten metal from molten metal holding chamber into tapping chamber by natural flow down) [0223] 13F: melt level sensor (for detecting upper limit level of molten metal in molten metal holding chamber) [0224] 13G: melt level sensor (for detecting lower limit level of molten metal in molten metal holding chamber for forcibly transferring molten metal from molten metal holding chamber into tapping chamber) [0225] 16: tapping chamber [0226] 16A: gas supply part [0227] 16B: thermocouple [0228] 16C: tapping chamber lid [0229] 16D: tapping chamber vessel [0230] 16E: melt level sensor (for detecting upper limit level of molten metal in tapping chamber) [0231] 16G: gas supply/exhaust part [0232] 50: control section [0233] MM: molten metal [0234] FS: front side [0235] BS: back side [0236] HD: height direction [0237] DS: down side [0238] US: upper side [0239] WD: width direction [0240] LS: left side [0241] RS: right side