JP5066018B2 - Casting method - Google Patents

Description

  The present invention relates to a casting method for producing a metal casting from aluminum and alloys thereof.

  In a conventional casting method, first, for example, an aluminum ingot is put into a melting furnace or a melting crucible, and the ingot is raised to 700 to 800 ° C. to generate a molten metal. At this time, since the material once taken out to the atmosphere is melted, the metal oxide is mixed in the molten metal. In particular, when a metal that has been repeatedly dissolved or a metal material that is heavily oxidized is used, the mixed metal oxide increases, and the mechanical strength (elongation, tensile strength, etc.) of the generated material or product is low. Generate pinholes, cracks, etc.

Therefore, as disclosed in Patent Document 1, a method has been proposed in which metal oxide is removed from the molten metal by using titanium dioxide as a solvent when melting the ingot to improve the molten metal. It is also disclosed that this method can also separate metals in noro and dross that could not be separated with conventional solvents.
JP 2002-18553 A

  Using the method disclosed in Patent Document 1, metal oxide such as aluminum dross and titanium dioxide powder are put into molten magnesium chloride or sodium chloride, heated to a predetermined temperature in that state, dross etc. When the metal oxide is melted, the metal and oxide in the dross can be separated. However, when heated to a predetermined temperature, spherical molten metal is deposited from a plurality of locations from the metal oxide, the precipitated metal reacts with oxygen in the atmosphere, and the oxidation reaction proceeds in a chain with ignition. As a result, the deposited metal became an oxide, and a situation in which the metal aluminum component could not be sufficiently recovered occurred.

  Moreover, when the solvent containing titanium dioxide is used like patent document 1, titanium dioxide was also discarded with the casting iron by using titanium dioxide as a solvent which is a consumable item, and it was expensive.

  The present invention has been made in view of the above-mentioned problems of the prior art, and has studied a mechanism for removing metal oxides in the molten metal with titanium dioxide, thereby improving the quality of the molten metal and cast product more efficiently at a lower cost. An object of the present invention is to provide a casting method that can be used.

  First, as a result of previous studies by the present inventor, it has been found that titanium dioxide powder itself does not react with molten metal or metal oxide. On the other hand, titanium dioxide has a function of facilitating the separation of the metal oxide mixed in the molten metal from the molten metal or easily separating and recovering the metal component from the metal oxide. I found it experimentally. These results suggest that the titanium dioxide powder is acting catalytically.

  In addition, titanium dioxide powder was found to have a separation effect of metal oxides from metals, but as a result of research conducted on easily oxidizable metals such as aluminum, titanium dioxide promoted oxidation. I also understood that I have it. Therefore, under circumstances where molten metal is difficult to react with oxygen in the atmosphere, it was confirmed that titanium dioxide has a function of separating metal oxides and metal components even if it is a metal that is easily oxidized, such as aluminum. The invention has been completed.

The present invention takes into dross generated during aluminum casting crucible, sprinkle titanium powder and carbon powder dioxide to the dross that has been placed in the crucible, heating the dross in the crucible to the melting temperature of the aluminum Then, the aluminum and metal oxide powder are separated to form a molten metal of the aluminum .

  According to the casting method of the present invention, the quality of the cast product is improved by the action of titanium dioxide, the proportion discarded as soot by oxidation is reduced, and the yield is improved. Furthermore, metal scraps, dross, and other soot can be collected to efficiently recover the metal, contributing to the effective use of resources.

  In particular, the purity of the molten metal can be improved by separating the metal oxide mixed in the molten metal with titanium dioxide in the material. As a result, it is possible to obtain a product with few pinholes and cracks and high mechanical strength in the metal structure of the cast material or product.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 and 2 show a crucible 10 and a stirring rod 12. The crucible 10 of this embodiment accommodates an ingot of a metal such as copper, aluminum, or iron, and is placed in a melting furnace to melt the ingot.

This crucible 10 is formed of ceramics such as alumina and contains titanium dioxide (TiO ₂ ) in its composition. Titanium dioxide is sufficient if the titanium dioxide layer 10 a is provided at a constant thickness on at least the inner wall surface of the crucible 10, and may not be included in the entire crucible 10. A larger proportion of titanium dioxide is preferable, but in view of crucible strength, it is appropriately contained in an amount of about 5% to 60%, preferably 10% to 50%.

  As shown in FIG. 2, the stirring rod 12 also has a titanium dioxide layer 12a on the surface. The titanium dioxide layer 12a is formed by coating with a ceramic material containing titanium dioxide or by mixing titanium dioxide into the material of the stirring rod 12.

  In this embodiment, the crucible 10 and the stirring rod 12 are used by putting a molten metal material such as a metal lump, metal scrap or dross into the crucible 10 installed in the melting furnace. Then, when the melting furnace is turned on or the fuel is burned and the inside of the melting furnace is heated so that the temperature in the crucible 10 is equal to or higher than the melting point of the metal, molten metal that is a molten metal is generated in the crucible 10. Further, the molten metal may be appropriately stirred with the stirring rod 12. The melting temperature at this time is about 700 ° C. to 800 ° C. for aluminum, 1200 ° C. to 1250 ° C. for copper, and about 1400 ° C. to 1500 ° C. for iron.

  At the time of melting, it melts in an atmosphere in which the melting furnace is closed and oxygen is shut off. When stirring the molten metal, an inert gas such as argon gas is injected into the molten metal surface to block oxygen.

  As a result, the catalytic action of the titanium dioxide layer 10a on the wall surface of the crucible 10 and the titanium dioxide layer 12a of the stirring rod 12 suppresses oxidation of the molten metal, and the metal oxide is also separated from the metal component. As a result, a high-quality molten metal with low oxides can be produced at low cost without using a solvent for improving the molten metal.

  This is because the metal composition to be called a suboxide before becoming a metal oxide is oxidized or reduced by the catalytic action of titanium dioxide, and becomes a stable metal oxide or molten metal, which is separated from the molten metal or metal Return to. Furthermore, by stirring the molten metal, the titanium dioxide layer 12a comes into contact with the entire molten metal, and by its catalytic action, the metal oxide and the metal component are uniformly separated throughout, and a high-purity molten metal is generated.

  The metal thus obtained has a high mechanical strength and can provide a material or product with few blowholes, pinholes and cracks. The applicable metal is particularly suitable for aluminum, copper, iron, and alloys thereof, and can be applied to other metals, and the target metal is not selected.

  Next, another casting method will be described. In this embodiment, as shown in FIG. 3, a material such as copper, aluminum, iron, or other metal ingot or iron, dross 22, or the like is placed in the crucible 10, and the door on the upper surface of the melting furnace 14 is closed. , Block oxygen.

  In this state, when the coke 16 of the melting furnace 14 is burned and the inside is heated, molten metal is generated. At the time of melting, the atmosphere of the melting furnace 14 is closed and oxygen is shut off. However, as shown in FIG. 3 (a), oxygen in the atmosphere enters when stirring, so there is no possibility of argon gas or the like. An active gas is injected into the molten metal surface to block oxygen, and the mixture is stirred with the stirring rod 12 shown in FIG.

  When melted in this manner, when the metal is, for example, aluminum, a powdered cast iron appears on the surface of the molten metal and can be easily removed. And the molten metal which is this separated molten metal is cast into a mold, and a metal cast product is manufactured. The molten metal is 700 ° C. in the case of aluminum, 1250 ° C. in the case of copper, and 1500 ° C. in the case of iron.

  According to the casting method of this embodiment, due to the action of titanium dioxide, there is almost no slot or cast iron remaining in the molten metal, and no pinholes or cracks are generated in the metal casting. Accordingly, the quality of the cast product becomes extremely good, and a high-quality cast product can be manufactured at a low cost.

  Next, a casting method according to an embodiment of the present invention will be described. In this embodiment, as shown in FIG. 4, an aluminum dross is put in the crucible 10, and the entire dross 22 is heated by a propane gas burner 18. At this time, the titanium dioxide powder 21 is spread on the dross 22 and heated in the atmosphere.

  Then, as shown in FIG.4 (b), when only the titanium dioxide powder 21 is sprinkled, dross will become the white powder 24 of a metal oxide completely. On the other hand, as shown in FIG. 4 (c), when the carbon powder 23, which is a reducing agent that oxidizes itself and deprives oxygen, is sprinkled on the dross 22 together with the titanium dioxide powder 21, and heated, FIG. As shown, the aluminum metal component 26 was separated together with the white powder 24.

  Therefore, even when melting in the atmosphere, when titanium dioxide is added together with a reducing agent that is easily oxidized such as carbon, and the metal oxide is heated and melted, the metal component becomes an atmosphere of a difficult oxidation reaction, The metal composition, which is a suboxide before becoming a metal oxide, is reduced by the catalytic action of titanium dioxide, with its oxygen being deprived by the reducing agent. As a result, the metal component in the dross, the stable metal oxide and the metal component are separated, and the metal component can be recovered.

  Further, together with the metal oxide material to be melted at this time, magnesium chloride or sodium chloride may be melted and titanium powder may be charged. By heating to a predetermined temperature in this state and melting the metal oxide, the metal component and the metal oxide in the dross can be separated efficiently and the metal component can be recovered.

  In addition, this invention is not limited to the said embodiment, About the constituent material of casting tools, such as a stirring rod used for casting, and a handle, at least a surface layer is good also as a composition material which mix | blended titanium dioxide. Thereby, the molten metal which contact | connects this casting tool is improved, and the pinhole and crack of a cast are also suppressed like the above.

  Further, the casting apparatus and tools of the present invention are not limited to crucibles and stirring rods, and any member can be used as long as it is in contact with the molten metal before pouring into the mold. It can be applied to appropriate devices and tools such as flow paths.

  Next, examples will be described. In this example, an aluminum alloy was recovered from aluminum dross produced during the casting of an aluminum product using a casting apparatus having titanium dioxide layers 10a, 12a on the crucible 10 and the stirring rod 12. In this case, since the combustion reaction of aluminum that usually occurs at a high temperature occurs even at a low temperature (about 750 ° C.) due to the action of titanium dioxide, it was carried out in an environment where oxygen in the atmosphere was blocked with argon gas. In the experiment, while flowing a large amount of Ar gas in a crucible furnace (coke combustion type) having a titanium dioxide component on the inner wall surface, the aluminum dross was melted by stirring with a titanium dioxide stirring rod 12 to recover the aluminum alloy.

  The dross used here was supposed to contain an aluminum metal component of less than 20% according to the preliminary evaluation by thermal analysis of the component.

  In this example, the experiment was performed twice, and the aluminum recovery was 33% and 32% in mass ratio. The dissolution temperature of alumidoros was 700 ° C to 900 ° C.

  According to this example, aluminum was recovered at a higher recovery rate than the expected aluminum metal component.

  Next, the aluminum alloy ingot and the dross produced during the casting of aluminum were respectively melted using the method of the present invention and tools.

When the material was heated and titanium dioxide was added, all the dross became powdery, and the inside of the furnace became about 800 ° C. Magnesium chloride powder was sprinkled on this, and a molten aluminum metal was obtained from the dross, and aluminum could be recovered, and a tensile test piece was created. The results are shown in Table 1. The result of the test piece obtained by melting the aluminum ingot is also shown.

Here, the standard value of the sand mold casting of tensile strength was 147 N / mm ² , and it was found that the aluminum test piece manufactured from the dross of this example had good performance.

  Next, other aluminum alloy ingots and dross produced during aluminum casting were each melted using the method and tool of the present invention.

The material was heated as above and the aluminum metal was melted using a tool coated with titanium dioxide. Moreover, aluminum can be collect | recovered from aluminum dross and the test piece was created. The results are shown in Table 2. The result of a test piece obtained by melting an aluminum ingot with a conventional apparatus is also shown.

  From the above results, it was found that a high-quality aluminum cast product can be obtained even when the titanium dioxide powder is not sprinkled.

It is a perspective view of a crucible used for casting. It is sectional drawing of a crucible and a stirring rod. It is a schematic sectional drawing which shows the casting method which interrupted | blocked oxygen . It is a schematic sectional drawing which shows the casting method of embodiment of this invention.

10 Crucible 10a, 12a Titanium dioxide layer 12 Stirring rod 14 Melting furnace

Claims (1)

Put dross generated during the casting of the aluminum crucible, sprinkle titanium powder and carbon powder dioxide to the dross that has been placed in the crucible, and heating the dross in the crucible to the melting temperature of the aluminum, the A casting method characterized in that aluminum and metal oxide powder are separated to form a molten aluminum .

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