The present invention relates to a conductive molten metal conveyance apparatus, a conductive molten metal conveyance system, and a conductive molten metal conveyance method.
Conventionally, there is performed manufacturing of, for example, a cast product (a round bar-shaped ingot or the like) with a molten metal having conductivity (conducting property), that is, a molten metal of non-ferrous metal (for example, Al, Cu, Zn or Si, or an alloy of at least two of them, or an Mg alloy, or the like) or a molten metal of other than non-ferrous metal.
In obtaining this cast product, it is common practice to guide the molten metal from a melting furnace with a trough and pour the molten metal into a mold.
Moreover, the present inventor has disclosed in Patent Literature 1 that a molten metal flowing in a trough is driven and conveyed by Lorentz force according to Fleming's left-hand rule.
Patent Literature 1: Japanese Patent No. 4772407
According to the technique disclosed in Patent Literature 1, by driving the molten metal in the trough by Lorentz force, it is possible to more reliably drive and convey the molten metal without relying only on gravity.
However, when the amount of the molten metal in the trough decreases and the liquid level drops below the positions of electrodes, the Lorentz force can no longer be obtained, and as a matter of course, the molten metal cannot be driven.
To prevent this, for example, the following measure may be taken. That is, it is just necessary to lower the positions of the electrodes, or to form the electrodes in plate shapes so that lower ends of the electrodes reach an inner surface of a bottom wall of the trough.
However, in any of the above cases, it is difficult to completely drive and convey the molten metal in the trough by the Lorentz force to completely discharge the molten metal from the trough even in a final stage of a work. That is, as the molten metal, normally, it can happen that numerous drop-shape or island-shape molten metals remain here and there on a bottom wall 5c of the trough 5, for example, as illustrated in
For this reason, at a site in practice, many workers manually scrape the molten metal from the trough before the molten metal is solidified just before the end of conveyance. Such an operation is extremely dangerous because the molten metal has a high temperature and it must be performed in a short time. However, such an operation is an indispensable work, not limited to the case of Patent Literature 1, when the molten metal is conveyed using the trough.
The present invention has been made in view of the above, and an object thereof is to provide a conductive molten metal conveyance apparatus, a conductive molten metal conveyance system, and a conductive molten metal conveyance method capable of driving and conveying a molten metal so that the molten metal does not remain in the trough as much as possible when the trough is used for conveyance.
A conductive molten metal conveyance apparatus according to an embodiment of the present invention is
a conductive molten metal conveyance apparatus that drives a target conductive molten metal that is a drive target by Lorentz force, the apparatus including:
a trough that has at least a molten metal storage space defined by a pair of side walls laterally facing each other at a predetermined distance and a bottom wall connecting the side walls, and is formed by a fire resistant and conductive material; and
a magnetic field device that is arranged below the bottom wall of the trough, and has an upper surface side that vertically opposes the bottom wall and is magnetized to a north pole or a south pole, in which magnetic field strength is set to strength such that magnetic force lines exiting from the magnetic field device or entering the magnetic field device run vertically in the molten metal storage space and the target conductive molten metal stored in the molten metal storage space in a state of penetrating the bottom wall,
in which by setting an electric resistance value of the trough to a value larger than an electric resistance value of the target conductive molten metal stored in the molten metal storage space, in a non-driving state where the target conductive molten metal is not present in the molten metal storage space, a current flows through a first current path from one side wall of the pair of side walls to another side wall through the bottom wall, and in a driving state where the target conductive molten metal is present in the molten metal storage space, a current flows through a second current path from the one side wall through a middle part of the first current path and bypasses to the target conductive molten metal, and thereafter returns to the first current path again, and in the driving state, in the target conductive molten metal, magnetic force lines running vertically and the current running horizontally cross each other to generate a Lorentz force, and the Lorentz force drives and carries the target conductive molten metal in the trough.
A conductive molten metal conveyance system according to an embodiment of the present invention includes a plurality of the conductive molten metal conveyance apparatuses described above, in which the plurality of conductive metal conveyance apparatuses are connected in series so that it is possible to supply a target conductive molten metal conveyed by the conductive molten metal conveyance apparatus in a preceding stage to the molten metal storage space of the conductive molten metal conveyance apparatus in a next stage.
A conductive molten metal conveyance method according to the present invention is
a conductive molten metal conveyance method that drives a target conductive molten metal that is a drive target by Lorentz force, the method including:
preparing a trough that has at least a molten metal storage space defined by a pair of side walls laterally facing each other at a predetermined distance and a bottom wall connecting the side walls, and is formed by a fire resistant and conductive material;
arranging a magnetic field device below the bottom wall of the trough, the magnetic field device having an upper surface side that vertically opposes the bottom wall and is magnetized to a north pole or a south pole, in which magnetic force lines exiting from the magnetic field device or entering the magnetic field device run vertically in the molten metal storage space and the target conductive molten metal stored in the molten metal storage space in a state of penetrating the bottom wall; and
by setting an electric resistance value of the trough to a value larger than an electric resistance value of the target conductive molten metal stored in the molten metal storage space, in a non-driving state where the target conductive molten metal is not present in the molten metal storage space, causing a current to flow along a first current path from one side wall of the pair of side walls to another side wall through the bottom wall, and in a driving state where the target conductive molten metal is present in the molten metal storage space, causing a current to flow through a second current path from the one side wall through a middle part of the first current path and bypass to the target conductive molten metal, and thereafter return to the first current path again, and in the driving state, in the target conductive molten metal, causing the magnetic force lines running vertically and the current running horizontally to cross each other to generate a Lorentz force, and by the Lorentz force, driving and carrying the target conductive molten metal in the trough.
One of characteristics of an embodiment according to the present invention is that an entire trough is formed by a conductive material, as will be described later. However, this is a configuration that cannot be employed by those skilled in the art other than the present inventor even if the above-mentioned Patent Literature 1 is publicly known. The reason is that in order to obtain the Lorentz force for driving molten metal in the trough, it is necessary to pass a current across a pair of electrodes opposing each other through the molten metal interposed between the electrodes. However, if the entire trough is formed by a conductive material, it is intuitively sensed that the current flows through only the trough and it is impossible to take a path of current to flow from one electrode into the molten metal and return again to the other electrode.
Moreover, the present inventor actually conducted an experiment for confirming whether or not the current really takes a path as illustrated in
That is, by this molten metal conveyance apparatus 1, the molten metal M having conductivity (conducting property) poured from the melting furnace 2, that is, a molten metal of non-ferrous metal (for example, Al, Cu, Zn or Si, or an alloy of at least two of them, or an Mg alloy, or the like) or a molten metal of other than non-ferrous metal is conveyed from left to right in the view and stored in a container 3.
Details of the molten metal conveyance apparatus 1 are illustrated in a more understandable manner in
Long bump-shaped terminals (electrodes) 8 are attached respectively outside the pair of side walls 5a.
The terminals 8 are formed by a high-conductivity material such as copper, and is for enhancing electrical conductivity between the trough 5 and cables 9. That is, the terminals 8 are connected to a power control panel 11 installed outside by the cables 9. This power control panel 11 supplies a current to the pair of terminals 8, and is configured so that a current value, a voltage value, and a frequency thereof can be adjusted and a polarity can be switched. This power control panel 11 is basically used as a direct current supply device in the embodiment of the present invention.
A magnetic field device 12 is arranged below the trough 5. The magnetic field device 12 includes a permanent magnet or an electromagnet. The magnetic field device 12 is magnetized to an N pole at an upper side and an S pole at a lower side. Thus, for example, as can be seen from
Next, the flow of current in the conductive molten metal conveyance system 100 configured as described above will be described.
First, in a state that the molten metal M does not exist in the trough 5 (non-driving state), as illustrated in
In a state that the molten metal M is poured from the melting furnace 2 into the trough 5 (driving state), the current I flows as illustrated in
Even when the current I flows as illustrated in
That is, as will be described later, according to the apparatus of the embodiment of the present invention, the current I can be reliably passed through the molten metal M regardless of the amount of the molten metal M. Thus, the current I and the magnetic force lines ML can be reliably crossed, and the molten metal M can be reliably conveyed by the Lorentz force according to Fleming's left-hand rule and discharged from the trough.
This point will be described below. That is, the driving of the molten metal M in the trough 5 by the Lorentz force F according to Fleming's left-hand rule due to the above-described crossing of the flow of the current I and the magnetic force lines ML from the magnetic field device 12 will be described in detail.
First, in
Further, also in
In the first embodiment, the case where the molten metal M is conveyed in the horizontal direction has been described. According to a second embodiment of the present invention described next, as can be seen from
That is,
Note that although the molten metal conveyance apparatuses 1A, 1B used in
Note that in the embodiment illustrated in
Further, in any of the above-described embodiments, the molten metal M can be driven in a more suitable state by appropriately adjusting the current value, the voltage value, and the polarity by operating the power control panel 11.
Further, by passing a low-cycle alternating current (at 1 to 5 Hz or the like) from the power control panel 11, the molten metal M can be vibrated back and forth at low cycles along the conveyance direction. This vibration accelerates the rate at which gas mixed in the molten metal rises in the molten metal and facilitates the escape of the gas from the molten metal, and quality of the molten metal can be improved. Further, the molten metal may be vibrated back and forth in the conveyance direction as described above at any time before driving and conveying the molten metal or during driving and conveying the molten metal. This makes it possible to carry out more smoothly and reliably the driving and conveyance of the molten metal forward, and to achieve high efficiency of the molten metal conveyance.
The present inventor conducted the following experiment in order to confirm the operation and effect of the conductive molten metal conveyance apparatus of the present invention.
That is, the present inventor conducted an experiment under the following conditions using what is called a low melting point alloy having the same characteristics as a molten metal such as aluminum.
At this time, 150 Kg/min (=9000 Kg/h) was obtained as the conveyance amount in the experiment.
At the end of conveyance, the inside of the trough was confirmed, but no molten metal remaining in the groove of the trough 5 was observed. In other words, the molten metal ascended the sloped trough 5 to the last drop and was discharged from the outlet.
The following effects can be obtained by the conductive molten metal conveyance apparatus according to the embodiments of the present invention described above.
1. It is possible to prevent damage to the apparatus due to thermal shock. That is, as illustrated in
2. No special and complicated operation is required to preheat the trough. That is, it is sufficient to simply energize the trough 5 for residual heat.
3. By connecting a plurality of molten metal conveyance apparatuses in series, it is possible to convey the molten metal over a longer distance.
4. It became possible to prevent a temperature drop of the molten metal during conveyance as much as possible. Just by energizing the trough 5 to drive the molten metal M, the trough 5 self-heats automatically. For this reason, when the molten metal M flows in the trough 5, the molten metal M runs in the heated trough 5, and it is possible to prevent the temperature of the molten metal M from decreasing during conveyance, and to reliably convey the molten metal.
5. The amount of molten metal remaining in the trough at the end of conveyance can be substantially eliminated, and the amount of molten metal M in the trough 5 can be reduced to the limit.
6. Since the molten metal M remaining in the trough 5 after use can be substantially eliminated, cleaning of the trough is substantially unnecessary.
7. The conveyance amount of the molten metal can be arbitrarily adjusted by controlling the current I in the power control panel 11.
8. Since the electrodes 8 are provided outside the pair of side walls 5a of the trough 5, the electrodes 8 do not come in contact with the molten metal M. Therefore, wear of the electrodes 8 can be suppressed as much as possible, and there is no need to replace the electrode.
Based on the above description, those skilled in the art may conceive additional effects and various modifications of the present invention, but the aspects of the present invention are not limited to the individual embodiments described above. Components may be suitably combined across different embodiments. Various additions, changes and partial deletions are possible without departing from the conceptual idea and spirit of the present invention derived from the contents defined in the claims and the equivalents thereof.
Number | Date | Country | Kind |
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2018-088830 | May 2018 | JP | national |
Number | Date | Country | |
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Parent | PCT/JP2019/017463 | Apr 2019 | US |
Child | 17083456 | US |