JP3624682B2 - Metal cleaning methods - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a metal cleaning method for removing non-metallic inclusions from a metal containing non-metallic inclusions.
[0002]
[Prior art]
FIG. 5 shows a block diagram of a melting furnace applied to a conventional metal cleaning method. In FIG. 5, 1 is a crucible made of a refractory such as alumina, silica, or magnesium, for example, 2 is an induction coil that inductively melts the metal charged into the crucible 1 to form a molten metal 3, and 4 is the metal. Non-metallic inclusions contained therein are shown. In FIG. 5, the metal containing the nonmetallic inclusions 4 is put into a crucible 1 made of a refractory and is induction-melted by the induction coil 2 to become a molten metal 3.
[0003]
In the above configuration, the metal cleaning method for removing the non-metallic inclusions 4 from the metal first involves pushing the metal toward the center of the furnace by the electromagnetic force from the induction coil 2, and the non-metallic inclusions 4 Since electromagnetic force does not work, it is divided into what remains in the vicinity of the furnace wall and what is pushed by the metal and pushed to the center of the furnace, but it floats on the surface of the molten metal due to the difference in specific gravity from the metal (metal, When the specific gravity difference from non-metallic inclusions is small, for example, when aluminum containing non-metallic inclusions is contained in aluminum, it is necessary to perform a sedation process in which the hot water movement is weakened and the floating of the alumina is gently waited. The slag trapping agent is entangled with this, and the nonmetallic inclusions 4 that have become slag are aggregated in a bowl shape. Next, the slag aggregated like a bowl is taken out of the crucible 1 entangled with the slag scraping bar, removed from the slag scraping bar and solidified. This slag scraping operation is repeated until the slag disappears from the surface of the molten metal 3. Thereafter, if the molten metal 3 is discharged and cast, a metal containing almost no non-metallic inclusions can be obtained.
[0004]
[Problems to be solved by the invention]
By the way, in the conventional method, the slag trapping agent is sprayed to remove non-metallic inclusions in the molten metal, and the slag is made into a bowl shape and scraped off. In addition, it takes time and effort to remove the slag adhering to the scraping rod, and further, in order to sufficiently capture the slag, there is a problem that time and labor are required since it is necessary to repeatedly spray the slag capturing agent and scrape the slag.
[0005]
The present invention has been made to solve the above problems, and an object of the present invention is to provide a metal cleaning method for easily removing non-metallic inclusions from a metal containing non-metallic inclusions. .
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 includes a non-metallic inclusion in a metal cleaning method in which a metal containing a non-metallic inclusion is dissolved to remove the non-metallic inclusion in the metal. A crucible made of a highly conductive metal having a metal outlet to be formed in a cylindrical shape with a bottom and from which molten metal is discharged to the bottom, and vertically long slits provided radially at substantially equal intervals in the cylindrical part, and the crucible It melts in a levitation melting furnace formed by winding an induction coil on the outer diameter side, weakens the levitation force before pouring and brings the molten metal and the crucible into contact with each other to solidify the molten metal surface of the contact portion. The hot water is discharged from the outlet.
[0007]
When a metal containing non-metallic inclusions is melted in a flotation melting furnace, the metal in the vicinity of the crucible wall is pushed into the center of the crucible receiving the electromagnetic repulsive force, but the non-metallic inclusion is different from the metal and the electromagnetic repulsive force from the crucible Since it does not receive, the density | concentration of the nonmetallic inclusion in the molten metal near the crucible wall surface becomes high. They move to the center of the crucible, which is moved by the movement of the metal pushed into the center of the crucible receiving the electromagnetic repulsive force, and float on the surface of the molten metal due to the difference in specific gravity from the molten metal, and remain near the crucible wall surface. However, non-metallic inclusions are hardly mixed in the molten metal. As a result of the experiment, iron containing non-metallic inclusions (alumina fine particles) was melted by a flotation melting furnace, cooled in a crucible, taken out from a crucible that had been solidified, cut vertically, and the cross section was observed. It was confirmed that alumina was concentrated in the portion corresponding to the vicinity of the outer periphery of the upper surface at the time of the molten metal and the portion in contact with the crucible wall. In addition, the iron mixed with 1% by mass of alumina is melted in a levitation melting furnace, the levitation force is weakened before pouring and the molten metal is brought into contact with the crucible to solidify the side surface of the molten metal, and then the molten metal The mass% of alumina was 0.004%, and the mass% of alumina in the metal adhering to the crucible side wall was 7%. Therefore, after the metal containing non-metallic inclusions is melted in the levitation melting furnace by the above method, the molten metal is brought into contact with the crucible to solidify the surface, and then the molten metal at the center is discharged to remove the non-metallic inclusions. It becomes possible to clean the contained metal.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram showing the main part of an embodiment of the present invention. In FIG. 1, members denoted by the same reference numerals as those of the conventional example have approximately the same functions, and thus description thereof is omitted. In FIG. 1, 3 is a molten metal in which a metal containing non-metallic inclusions 4 is melted, and 5 is a structure in which two or more electrically insulated segments are arranged side by side through an insulator in the circumferential direction. It is a crucible that forms an outlet 5a. The inside of the crucible 5 is hollowed out, and a metal to be melted is placed in this portion. An upper induction coil 6 and a lower induction coil 7 are wound around the outer peripheral side of the crucible 5, and a high frequency current is supplied from AC power supplies 8 and 9, respectively. 11 is a mold for casting the molten metal 3, 12 is a metal cast into the mold 11, and 13 is a solidified layer solidified by the molten metal 3 coming into contact with the wall surface of the crucible 5.
[0009]
In FIG. 1, a metal containing non-metallic inclusions 4 is placed in a crucible 5. As shown in the principle diagram of the flotation melting furnace in FIG. 2, the magnetic flux generated in the induction coils 8 and 9 is An eddy current is induced by interlinking with each electrically insulated segment, and also enters the crucible 5 through the gap of the slit and interlinks with the molten metal 3 containing the nonmetallic inclusions 4. An eddy current is induced in the molten metal 3. Since the directions of the eddy currents flowing through the crucible 5 and the molten metal 3 are opposite to each other at the opposing surface portions, they are magnetically repelling, and since the crucible 5 is fixed, the molten metal 3 has a levitation force. If this levitation force is greater than the weight of the molten metal 3, the molten metal 3 is lifted away from the crucible 5. Here, it is desirable that the molten metal 3 containing the nonmetallic inclusions 4 is stably positioned at the center of the crucible 5 in order to prevent contact with the crucible 5. In order to levitate stably in the crucible 5, it is necessary to increase the electromagnetic repulsion force from the crucible 5 that opposes the weight of the material to be melted toward the bottom of the crucible.
[0010]
In order to increase the electromagnetic repulsive force at the crucible bottom, the lower induction coil 7 wound on the outer diameter side of the crucible 5 has a low frequency (upper induction coil so that a higher levitation force than that of the upper induction coil 6 can be obtained. 6 to several tens of KHz, the lower induction coil supplies a current from an AC power source 9 of 7 KHz, and the upper induction coil 6 is supplied with a high frequency current for dissolving the material to be dissolved from another AC power source 8 Things have been done.
[0011]
Since the nonmetallic inclusions 4 contained in the molten metal 3 are electrically insulating, they do not receive a magnetic repulsive force unlike metals, and therefore remain in the vicinity of the wall surface of the crucible 5. They move to the center of the crucible, which is moved by the movement of the metal pushed into the center of the crucible receiving the magnetic repulsive force, float up due to the specific gravity difference with the molten metal, and float on the surface of the crucible 5 Although it separates into what remains in the vicinity of the wall surface (see FIG. 3), the non-metallic inclusions 4 hardly enter the molten metal inside.
[0012]
The molten metal 3 generates heat due to resistance loss and continues to be heated. Further, since the eddy current induced in the crucible 5 also heats the crucible 5, the crucible 5 is cooled with water so as not to melt.
The metal cleaning method is performed as follows. First, as described above, the metal containing the non-metallic inclusions 4 is melted by the levitating and melting apparatus so that the non-metallic inclusions 4 concentrate on the vicinity of the wall surface of the crucible 5 on the molten metal 3, and then the lower induction The current of the coil 7 is controlled to weaken the magnetic repulsion force on the molten metal 3 to bring the molten metal 3 into contact with the wall surface of the crucible 5, and the molten metal in that portion is solidified and adhered, and the remaining molten metal 3 is discharged from the outlet 5 a. The purpose is achieved by pouring out the hot water and casting it into the mold 11 and taking out the highly clean metal 12 from the mold 11.
[0013]
Next, when all of the molten metal has flowed out, the solidified layer 13 remains in the crucible 5 as shown in FIG. 4, so that the solidified layer 13 solidified and adhered to the wall surface of the crucible 5 is removed to prepare for the next melting.
The crucible is a water-cooled crucible made of copper. Since the molten metal does not melt even if it contacts, the solidified metal and the crucible are not welded, so that the metal can be easily removed from the crucible.
[0014]
【The invention's effect】
According to the present invention, the metal containing non-metallic inclusions is melted by the levitating dissolution apparatus and the non-metallic inclusions are attached to the crucible wall surface and removed, so that the slag is agglomerated and sprinkled out. Compared with the method, the work of removing non-metallic inclusions is facilitated, and there is an effect of increasing the removal rate of non-metallic inclusions.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of the main part of an embodiment of the present invention. FIG. 2 is a principle diagram of a levitation melting furnace. FIG. 3 is a state diagram immediately before tapping of a levitation melting furnace. Phase diagram of flotation melting furnace with adhesion [Fig.5] Configuration diagram of melting furnace applied to conventional metal cleaning method [Explanation of symbols]
3 Molten metal 4 Non-metallic inclusion 5 Crucible 5a Outlet 6 Upper induction coil 7 Lower induction coil 8, 9 AC power source 11 Mold 12 Metal 13 Solidified layer

Claims (1)

In a metal cleaning method in which a metal containing non-metallic inclusions is dissolved to remove non-metallic inclusions in the metal, the metal containing non-metallic inclusions is formed into a bottomed cylindrical shape at the bottom. Outflow outlet for discharging molten metal, a crucible made of a highly conductive metal having longitudinal slits provided radially at equal intervals in a cylindrical portion, and a floating melting furnace formed by winding an induction coil on the outer diameter side of the crucible The molten metal is melted at the bottom, and the levitation force is weakened before pouring, the molten metal and the crucible are brought into contact with each other, the molten metal surface of the contact portion is solidified, and the remaining portion is discharged from the outlet. Metal cleaning method.

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