JP2021081107A - Metal melting device - Google Patents

Abstract

To provide a metal melting device that melts a melting raw material having a specific gravity lighter than a molten metal without oxidizing the raw material.SOLUTION: A metal melting device includes: a melting chamber for supplying a melting raw material into a molten metal; and a heating chamber communicated to the melting chamber via a supply passage and having heating means for heating the molten metal. A screen plate for preventing a non-melted melting raw material transported from the supply passage from floating until it becomes at least a predetermined size is provided in the heating chamber.SELECTED DRAWING: Figure 1

Description

The present invention relates to a metal melting apparatus that melts a melting raw material in a molten metal, and in particular, melts a melting raw material such as aluminum, an aluminum alloy, and a non-ferrous metal in order to prepare a molten metal for supplying to a casting machine, a melting furnace, or the like. Regarding metal melting equipment.

Due to the growing awareness of environmental protection, the automobile industry and the like are promoting the weight reduction of members and devices by various casting products such as engine blocks. Along with this, the amount of lightweight non-ferrous metal materials such as aluminum materials and aluminum alloy materials is increasing.
For this reason, efforts are being made to reduce the amount of new materials used in the raw materials by using scrap materials such as return materials, briquette materials, and chips as the melting raw materials for the molten metal that manufactures castings.

Among scrap materials, briquette material is solidified by compressing cutting chips and chips generated from processing, and contains oil and water. Therefore, if it is supplied to the molten metal as it is, the oil will burn and exhaust gas will be emitted. Since it is generated, a pretreatment for evaporating oil, water, etc. contained in advance may be performed.

However, since the briquette material has a smaller specific density and a larger surface area than the molten metal, there is a problem that even if the pretreatment is performed, the briquette material easily floats on the surface of the molten metal and a part of the briquette material is easily oxidized during melting. And, for example, as _{the melting point of Al 2} O _{3 which is an oxide of aluminum is 2072 ° C., Al 2} O ₃ which is an oxide of a non-ferrous metal material such as an aluminum material has an extremely high melting point and is in a molten metal. When _{an oxide such as Al 2} O ₃ is formed in the molten metal, it does not dissolve in the molten metal and becomes a foreign substance, which deteriorates the quality of the casting.

On the other hand, as a technique for making it difficult for oxides to be formed when the briquette material is melted into a molten metal, the briquette material is melted by supplying the briquette material to the vortex of the molten metal as described in Patent Document 1 or 2 below. There is a technique to pull in quickly.

Japanese Unexamined Patent Publication No. 2013-60629 Japanese Unexamined Patent Publication No. 2-219978

However, even if the briquette material is drawn into the molten metal by the vortex flow, the drawn briquette material may not be completely dissolved and may be transferred to the next process without being dissolved.
Then, in such a case, the undissolved briquette material floats on the surface of the molten metal in the next step and is oxidized there.

Therefore, a main object of the present invention is to provide a metal melting apparatus that solves the above-mentioned problems of the prior art and melts a melting raw material having a lighter specific gravity than a molten metal such as a briquette material so as not to oxidize.

The means for solving the above problems are as follows.

The first means is
A melting chamber that supplies the melting raw material into the molten metal,
It has a heating chamber that communicates with the melting chamber via a supply path and has a heating means for heating the molten metal.
A screen plate is provided in the heating chamber to prevent the undissolved dissolved raw material transferred from the supply path from floating until it reaches at least a predetermined size.
It is a metal melting device characterized by the above.

The second means is
The screen plate has a large number of through holes, and the through holes are tapered from the bottom surface side to the top surface side, and is a metal melting device according to the first means.

The third means is
The first or second means is provided with an impact applying means for giving an impact to the undissolved dissolved raw material transferred from the melting chamber to the heating chamber in the vicinity of the supply passage or the supply passage of the melting chamber. It is a metal melting device.

The fourth means is
The impact applying means is a metal melting means according to the first to third means, which is an inner wall of the supply path configured so that the undissolved dissolved raw materials collide with each other or an inner wall in the vicinity of the supply path of the melting chamber. It is a device.

The fifth means is
The metal melting apparatus according to the first to fourth means, wherein the melting chamber is provided with a vortex generating means for generating a vortex in the molten metal in the melting chamber.

The sixth means is
The metal melting apparatus according to the fifth means, wherein the vortex generating means generates a vortex in the molten metal by ejecting a gas into the molten metal.

The seventh means is
The metal melting apparatus according to the sixth means, wherein the gas is an inert gas that is inert to the molten metal.

[Action effect]
According to the present invention, in order to melt a melting raw material having a lighter specific gravity than a molten metal such as a briquette material which is a scrap material of an aluminum alloy or a non-ferrous metal material, a screen plate is provided in a heating chamber. Since the molten raw material is prevented from floating on the surface of the molten metal, it is prevented from coming into contact with air or the like on the surface of the molten metal to be oxidized, and a clean molten metal with less oxide can be obtained. Further, the yield of the molten metal to be refined is improved, and the slag treatment work for the oxide treatment is also reduced.

Further, assuming that the screen plate has a large number of through holes and the through holes have a tapered shape narrowing from the bottom surface side to the top surface side, the dissolved raw material fits into the through holes and is predetermined. It can be held until it is large enough to be dissolved before it rises to the surface of the water, and can be dissolved without floating on the surface of the water so as not to be suitably oxidized.

Further, if an impact applying means for giving an impact to the undissolved dissolved raw material transferred to the heating chamber is provided near the supply path or the supply path of the melting chamber, the undissolved dissolved raw material is impacted by the impact applying means. It is easily dissolved by the time it is crushed and supplied to the heating chamber. In particular, if it is a material such as a briquette material that is solidified by compressing cutting chips, chips, etc., it is likely to collapse due to an impact, and dissolution can proceed particularly effectively.
If the impact applying means is a supply path or the like configured so that the undissolved dissolved raw materials collide with each other, the undissolved dissolved raw materials can be impacted simply and without creating a dynamic portion.

Further, if the melting chamber is provided with a vortex generating means for generating a vortex in the molten metal in the melting chamber, even if a scrap material having a light specific density such as a briquette material is supplied, they quickly reach the bottom of the vortex at the center of the vortex. Since it is drawn in, it becomes difficult to come into contact with the outside air, so that it becomes difficult for oxides to be formed and a cleaner molten metal can be obtained.

Further, if the vortex flow generating means is to generate a vortex flow in the molten metal by ejecting a gas into the molten metal, it is possible to prevent a stirring member such as a stirring blade or a stirrer from being present at the bottom of the center of the vortex, and it can be used as a melting raw material. The risk of contact with the stirring member is reduced to each stage, and not only the melting raw materials such as briquettes and chips, which have a lighter specific gravity than the molten metal, but also the melting raw materials that sink in the molten metal such as return materials and new materials are combined into the melting chamber. It will be able to be supplied and dissolved. Since the number of dynamic parts such as stirring blades and stirrers can be reduced, maintenance and handleability will be improved.

Further, if the gas is an inert gas that is inert to the molten metal, the degassing effect is exhibited, and a cleaner and higher quality molten metal can be obtained.

According to the present invention, there is provided a metal melting apparatus that melts a melting raw material having a lighter specific gravity than a molten metal such as a briquette material so as not to oxidize.

It is a top view of the plane of the melting holding furnace including the metal melting apparatus which concerns on this invention. FIG. 1 is a view taken along the line II-II in FIG. 1, which is a schematic cross-sectional view of a melting and holding furnace including the metal melting device according to the present invention. However, for convenience of explanation, members that do not appear in the II-II arrow are also described. It is a top view of the plan view of the melting holding furnace including another metal melting apparatus which concerns on this invention. FIG. 3 is a view taken along the line IV-IV in FIG. 3, which is a schematic cross-sectional view of a melting and holding furnace including another metal melting device according to the present invention. However, for convenience of explanation, members that do not appear in the IV-IV arrow are also described. It is sectional drawing for demonstrating the jet pump which concerns on this invention. It is a perspective view for demonstrating the screen board which concerns on this embodiment. It is a VI-VI sectional view of another screen plate which concerns on this embodiment. It is a perspective view for demonstrating another screen board which concerns on this Embodiment. It is VIII-VIII sectional view of another screen plate which concerns on this embodiment. It is sectional drawing of the example of the melting chamber which concerns on this invention. It is sectional drawing of another example of the melting chamber which concerns on this invention. It is a top view of the plan of the melting holding furnace which includes another metal melting apparatus which concerns on this invention. FIG. 12 is an arrow view of XIII-XIII in FIG. 12, which is a schematic cross-sectional view of a melting and holding furnace including another metal melting device according to the present invention. However, for convenience of explanation, members and the like that do not appear in the XIII-XIII arrow are also described.

Hereinafter, embodiments according to the present invention will be described with reference to FIGS. 1 to 13.
The metal melting apparatus 10 according to the present embodiment has a melting chamber 11 for supplying the melting raw material B into the molten metal M, and a heating chamber 20 for heating the molten metal M by communicating with the melting chamber 11 via the supply path 13. ing. The metal melting apparatus 10 according to the present embodiment has a sedation chamber 30 that holds the molten metal M and precipitates impurities and the like in the molten metal M, an external casting machine that pumps out the molten metal M, and other melting and holding furnaces and holding. It is preferably incorporated in a melting and holding furnace 1 provided with a pumping chamber 40 for discharging hot water to a furnace or the like. A melting and holding furnace 1 incorporating the metal melting device 10 is also proposed as the present invention.

However, the metal melting device 10 of the present invention is not limited to the form incorporated in the melting and holding furnace 1 according to the present embodiment, and can be used alone or as a device for supplying and melting the melting raw material B into the molten metal M. It can be carried out by incorporating it into other types of melting and holding furnaces and melting furnaces.

In the melting and holding furnace 1 according to the present embodiment, each chamber is formed of a refractory material 2 in the outer shell 3, and the melting chamber 11 communicates with the heating chamber 20 via a supply path 13. Further, a circulation chamber 50 communicating with the heating chamber 20 and the melting chamber 11 is preferably provided, and the molten metal M is configured to be able to return from the heating chamber 20 to the melting chamber 11 via the circulation chamber 50.

The melting chamber 11 has a supply port 11A for supplying the melting raw material B upward, and is an aluminum or aluminum alloy which is the melting raw material B from a carry-in device such as a hopper or a conveyor (not shown) via the supply port 11A. And other non-ferrous metal materials are supplied to the molten metal M in the melting chamber 11. Specific forms of aluminum, aluminum alloys and other non-ferrous metal materials include scrap materials such as return materials, briquette materials and chips, and new materials. In particular, the metal melting apparatus 10 according to the present invention is suitable for a melting raw material B such as a briquette material which has a lighter specific gravity than the molten metal M and floats on the surface of the molten metal. The dissolved raw material B containing oil, water, etc. of the briquette material may be pretreated to remove the oil, water, etc. by drying and preheating in advance.

In the heating chamber 20, as a preferable form, immersion heaters 21 and 21 are arranged so as to be inserted into the heating chamber 20 from above to heat the molten metal M. By heating the molten metal M by the immersion heaters 21 and 21, the temperature of the molten metal M in the melting holding furnace 1 is maintained, and the melting raw material B supplied to the melting chamber 11 and the heating chamber 11 from the melting chamber 11 via the supply path 13 are used. The dissolution raw material B sent to No. 20 is dissolved in the molten metal M. However, the heating means of the molten metal M in the heating chamber 20 is not limited to the immersion heaters 21 and 21, and an immersion burner may be adopted. Further, the arrangement of the immersion heaters 21 and 21 is not limited to the form of inserting into the heating chamber 20 from above, but also the form of inserting into the heating chamber 20 from the side wall side of the heating chamber 20 as shown in FIGS. 12 and 13. It may be arranged in.

Further, the heating chamber 20 includes a melting chamber lid 22 installed by closing the upper opening so as not to create a space between the molten metal M and the surface of the molten metal M, and the melting chamber 20 is sent from the melting chamber 11. The raw material B is easily dissolved in an oxygen-free state. However, the heating chamber 20 according to the present invention does not necessarily have to be provided with a melting chamber lid 22 that does not form a space between the molten metal M and the surface of the molten metal M.

It is desirable that the outlet of the supply path 13 from the melting chamber 11 to the heating chamber 20 is located below the heating chamber 20, as shown in FIGS. 2, 4 and 13. By setting the outlet of the supply path 13 as the lower part of the heating chamber 20, for example, the melting raw material B having a lighter specific gravity than the molten metal, such as an undissolved briquette material that was not completely melted in the melting chamber 11, is heated. When supplied to the chamber 20, the molten metal M in the heating chamber 20 can be melted in the process of floating, and an event in which undissolved briquette material accumulates in the upper part of the heating chamber 20 and is oxidized is less likely to occur. .. Even if the upper opening is closed by the melting chamber lid 22 so as not to create a space between the molten metal M and the molten metal surface, a gas such as air is provided between the melting chamber lid 22 and the molten metal surface. In addition, in the dissolved raw material B containing oil and water such as briquette material, gas derived from water and oil may accumulate on the lower surface of the lid, so that the dissolved raw material B floats on the surface of the hot water. May be oxidized. Therefore, even when the upper opening is closed by the melting chamber lid 22 so as not to create a space between the molten metal and the surface of the molten metal, it is desirable that the outlet of the supply path 13 is located below the heating chamber 20. ..

In the metal melting apparatus 10 according to the present embodiment, as shown in FIGS. 2, 4 and 13, characteristically, the lower part where the outlet of the supply path 13 of the heating chamber 20 is located and the upper part above it. A screen plate 70 is provided in the heating chamber 20 to prevent the molten material B transferred from the supply path 13 from floating until it reaches at least a predetermined size.

As shown in FIGS. 6 to 8, the screen plate 70 is a plate-like body formed of a material that can be submerged and installed in the molten metal M and has a large number of through holes 71, and is a plate-like body having a large number of through holes 71, and is a supply path 13 from the melting chamber 11. The undissolved dissolved raw material B supplied into the heating chamber 20 through the screen plate 70 is placed at a position particularly below the screen plate 70 in the heating chamber 20 until it becomes large enough to pass through the through hole 71 formed in the screen plate 70. Hold it so that the dissolution proceeds in the molten metal M. However, the screen plate 70 is not limited to this, and is not particularly limited as long as it prevents the melting raw material B having a specific gravity lighter than that of the molten metal M from floating.

By providing the screen plate 70 in the heating chamber 20 in this way, it is possible to prevent the melting raw material B, which has a lighter specific gravity than the molten metal such as briquette material, from floating up to the surface of the molten metal in the heating chamber 20. It becomes possible to dissolve in anoxic state.

The number and size of the through holes 71 formed in the screen plate 70 are not particularly limited, but the size and dissolution rate of the dissolved raw material B to be supplied, the distance between the installation depth of the screen plate 70 and the molten metal surface, and the melting raw material It may be determined appropriately in consideration of the property of B and the like. The melting raw material B having a size that allows it to pass through the through hole 71 may be set so as to be sufficiently dissolved by the molten metal before it floats on the surface of the molten metal. Preferably, it is desirable to design so that the time until the undissolved dissolved raw material B floats through the through hole and is dissolved before reaching the surface of the molten metal is 2 to 3 minutes. For example, considering the general size of a briquette material from an aluminum scrap material, it is desirable that the through hole 71 has a diameter of 20 to 50 mm.

Further, it is desirable that the through hole 71 has a cylindrical shape as shown in FIGS. 6 and 7, or a tapered shape that narrows upward as shown in FIGS. 8 and 9. With this configuration, the undissolved raw material B fits into the through hole 71, stays in a fixed position without moving in the heating chamber 20, and the dissolution facilitates.

The material of the screen plate 70 may be any material that can be submerged and installed in the molten metal M, but is preferably silicon carbide, zirconia, or fine ceramics.
The thickness of the screen plate 70 is not particularly limited, but if it is the above material, it is easy to obtain sufficient strength if it is 20 to 80 mm.

The screen plate 70 may be installed in the heating chamber 20 so as to be fixed to the bottom of the heating chamber 20 or suspended from the top surface of the heating chamber 20. The installation method is not limited. However, if the immersion heaters 21 and 21 are arranged so as to be inserted into the room from above as in the heating chamber 20 of the embodiment, the screen plate 70 is provided so that the immersion heaters 21 and 21 and the floating melting raw material B do not come into contact with each other. Is preferably placed below the bottom of the immersion heaters 21 and 21. Further, the screen plate 70 is preferably provided at a height of 20 to 35% from the bottom of the heating chamber 20. Further, as shown in FIG. 4, a plurality of screen plates 70 may be provided in the heating chamber 20. In this case, the hole diameter of the through hole 71 of each screen plate 70 may be different. In that case, it is desirable that the diameter of the through hole 71 of the upper screen plate 70 be smaller than the diameter of the through hole 71 of the lower screen plate 70.

On the other hand, the metal melting apparatus 10 according to the present invention is an impact applying means for giving an impact to the undissolved dissolved raw material B sent from the melting chamber 11 to the heating chamber 20 in the vicinity of the supply passage 13 or the supply passage 13 of the melting chamber 11. It is desirable to provide. The impact applying means may dynamically apply an impact, but preferably, in terms of maintainability, the undissolved dissolved raw material B collides in the process of being conveyed to the heating chamber 20 by the flow of the molten metal. It is desirable that it is a static object such as an obstacle that does. For example, a convex portion may be provided on the inner wall of the supply path 13 or the inner wall in the vicinity of the supply path 13 of the melting chamber 11 so that the undissolved dissolved raw material B collides with the convex portion when passing through. Further, as a specific example, the undissolved dissolved raw material B such as a briquette material having a lighter specific gravity than the molten metal M is along the upper surface of the supply path 13 due to the buoyancy and the flow of the molten metal M into the heating chamber 20. As shown in FIGS. 2, 4 and 13, if the upper wall surface 13B of the supply path 13 is formed in a stepped shape or a convex portion is formed on the upper wall surface 13B, it is not possible. When the dissolution raw material B for dissolution moves to the heating chamber 20, it collides with the stepped upper wall surface 13B of the supply path 13 and the convex portion formed on the upper wall surface 13B, and an impact is applied to the undissolved dissolution material B. The raw material B collapses and is easily melted quickly in the heating chamber 20 in which the screen plate 70 is installed.

On the other hand, in the metal melting apparatus 10 according to the present invention, it is desirable that the melting chamber 11 is provided with a vortex generating means for generating a vortex in the molten metal M in the melting chamber 11. As the vortex generating means, as shown in FIGS. 1 to 4 and 12 to 13, it is desirable that the vortex is generated in the molten metal M by ejecting the gas G into the molten metal M. As shown in FIG. 10, a magnetic stirring device 114 may be provided below the melting chamber 11 to generate a vortex in the molten metal M in the melting chamber 11. Further, as shown in FIG. 11, a stirring device provided with a stirring blade 116 at the tip of the rotating shaft 115 is inserted into the molten metal M of the melting chamber 11, and the molten metal M is stirred by the stirring blade 116 to generate a vortex. It may be made like this. In this embodiment, the degassing treatment may be performed by injecting the inert gas G, which is inert to the molten metal M, from the tip of the rotating shaft 115. By generating a vortex flow in the molten metal M in the melting chamber 11 as in these forms, even if the melting raw material B having a lighter specific density than the molten metal M is supplied, they are quickly drawn into the vortex bottom at the center of the vortex. As a result, the melting raw material B and the outside air are less likely to come into contact with each other, and oxides are less likely to be formed, so that a cleaner molten metal M can be obtained. Further, in the process in which the dissolved raw material B is agitated by the vortex flow, the collision between the dissolved raw materials B is promoted and the dissolved raw materials B are easily dissolved by the collapse. In particular, in a briquette material obtained by compressing and solidifying cutting chips and chips, collapse occurs effectively.

The shape of the melting chamber 11 may be a rectangular box shape, but if a vortex is to be generated, the shape of FIG. 1 is particularly high.
As shown in No. 4 and FIGS. 12 to 13, it is desirable that the inner space in which the molten metal M is stored is a substantially cylindrical shape or a substantially inverted conical shape. The molten metal M is flowed so as to be guided by the inner wall surface, so that a vortex of the molten metal M is likely to be generated in the melting chamber 11 and the vortex is easily maintained. Therefore, it is possible to reduce the energy related to the gas ejection.

Further, when the melting chamber 11 is to generate a vortex, the melting chamber side opening 13A of the supply path 13 connecting the melting chamber 11 and the heating chamber 20 is formed at the central bottom of the vortex, for example, FIGS. 2 and 4. And, as shown in FIG. 13, it is desirable to form it at the central bottom of the dissolution chamber 11. The dissolved raw material B is drawn into the center of the vortex bottom by the vortex flow, and the dissolved raw material B is supplied to the heating chamber 20 without floating, so that the dissolved raw material B is effectively melted.

Further, it is desirable that the melting chamber 11 is provided with a molten metal heating means for heating the molten metal M. Although not shown, the molten metal heating means may be provided with a dipping heater at the bottom of the melting chamber 11 or near the side wall. The immersion heater may be arranged so as to be inserted into the molten metal M from above near the side wall of the melting chamber 11. If the molten metal heating means is provided in the melting chamber 11, the molten metal M stored in the melting chamber 11 is heated, the temperature drop of the molten metal M due to the supply of the melting raw material B is reduced, and the melting raw material B is easily melted more quickly. Become. Further, a dipping burner may be used instead of the dipping heater.

Subsequently, as a vortex generating means which is a particularly preferable form in the melting chamber 11 according to the present invention, a specific form for generating a vortex in the molten metal M by ejecting the gas G into the molten metal will be described.
As shown in FIGS. 1 to 4, the melting chamber 11 characteristically creates a vortex in which the gas G is ejected into the molten metal M in the melting chamber 11 and the molten metal B is stirred together with the molten metal M. A gas ejection device 14 for generating gas inside is provided, and the metal melting device 10 is configured together with the heating chamber 20.

As shown in the figure, the gas ejection device 14 is, for example, an ejection portion 14B having an ejection port 14A located in the molten metal M, an air supply pipe 14C communicating with the ejection portion 14B, and a gas generator 14D for generating gas G. Can be configured. For example, when the gas is nitrogen gas, examples of the gas generator include "nitrogen gas generator (N2 pack)" manufactured by Hitachi Industrial Equipment Systems Co., Ltd. and equivalent devices manufactured by Anest Iwata Co., Ltd. By ejecting the gas G sent from the gas generator 14D into the melting chamber 11 via the air supply pipe 14C from the ejection port 14A into the molten metal M, the molten metal M in the melting chamber 11 is agitated and a vortex is generated. Let me.

Further, although not shown, a straightening vane may be provided in the melting chamber 11 to guide the gas G ejected from the ejection port 14A in an appropriate direction to facilitate the generation of a vortex flow. For example, a straightening vane protruding from the inner wall of the melting chamber 11 toward the center of the melting chamber 11 is provided at a position immediately above the ejection port 14A. The gas G ejected from the ejection port 14A becomes bubbles and does not rise immediately, so that a vortex flow is likely to occur. At this time, if the straightening vane is tilted so as to move slightly upward as the distance from the ejection port 14A side increases, the gas G is injected in a substantially spiral direction, and it becomes easier to generate a vortex flow. Further, a groove may be formed spirally on the inner wall of the melting chamber 11. In this way, eddy currents are more likely to occur.

In the gas ejection device 14 of the present embodiment, it is desirable that the ejection portion 14B is provided in the vicinity of the inner wall surface in the melting chamber 11 as shown in FIGS. 1 and 2, 12 and 13. The supplied melting raw material B is drawn to the center of the vortex flow by the vortex flow. If the ejection portion 14B is near the inner wall surface, the dissolution raw material B is less likely to come into contact with the ejection portion 14B, and the risk of damage to the gas ejection device 14 is reduced.

Further, as shown in FIGS. 3 and 4, the gas ejection device 14 is provided in the side wall of the dissolution chamber 11 so as to be less likely to come into contact with the dissolution raw material B, and the ejection port 14A is provided in the dissolution chamber 11 from the wall surface. You may try to face. In the embodiment shown in FIGS. 3 and 4, the melting chamber 11 is a part of the melting holding furnace 1, and the circulation chamber 50 and the circulation passage are provided so that the molten metal M returns from the heating chamber 20 to the melting chamber 11. Therefore, the molten metal M is circulated from the heating chamber 20 to the melting chamber 11, such as between the walls between the melting chamber 11 and the circulation chamber 50, that is, the communication passage 51 between the melting chamber 11 and the circulation chamber 50. A spouting portion 14B is provided in the road so that the spouting port 14A faces the melting chamber 11. By doing so, the ejection portion 14B is not located in the melting chamber 11, the contact between the ejection portion 14B and the dissolution raw material B is effectively prevented, and the risk of damage to the gas ejection device 14 is further reduced. ..

As shown in FIGS. 1 to 4, the desired direction of the gas G ejection port 14A, that is, the gas ejection direction, may be set so that the center of the generated vortex flow is the central portion of the melting chamber 11. For example, if the melting chamber 11 has a substantially circular diameter in a plan view as shown in the illustrated example, it may be oriented in the substantially tangential direction of the circle.

Further, as shown in FIGS. 1 and 2, FIG. 12 and FIG. 13, the ejection portion 14B is provided at a depth position near the bottom portion in the melting chamber 11, and the ejection port 14A is directed slightly upward so that the ejection port 14A is directed slightly upward. If the gas G ejected from the gas G is ejected from the side of the bottom of the dissolution chamber 11 in a spiral direction with respect to the central portion of the dissolution chamber 11, it becomes easier to generate a vortex in the dissolution chamber 11. The ejection direction of the gas G shown in the figure is an example in which the central portion of the melting chamber 11 is set to be the center of the vortex, but of course, the center of the vortex flow is set to be different from the central portion of the melting chamber 11. In this case, the ejection port 14A and the ejection portion 14B may be appropriately provided so that the gas G is ejected in the spiral direction with respect to the center of the vortex flow.

It is desirable that the number of gas G ejection points in the dissolution chamber 11 is a plurality. In the illustrated form, it is provided in two places. When there are a plurality of ejection points, one gas ejection device 14 having a plurality of ejection ports 14A may be provided in the dissolution chamber 11, or a plurality of gas ejection devices 14 may be provided in the dissolution chamber 11. Good. If the gas G is ejected from a plurality of places, a larger stirring force for the molten metal M can be generated, so that a vortex flow is likely to occur. In this case, if the ejection port 14A is arranged at a point-symmetrical position with respect to the center of the vortex to be generated, for example, the central portion of the melting chamber 11, the vortex can be more easily generated. Further, when there are a plurality of ejection points, eddy currents are more likely to occur if the depth positions of the ejection points are different. If it is a general melting chamber 11, the depth of one ejection portion is preferably 350 to 400 mm, and the other ejection portion is preferably 170 to 230 mm.

The gas ejection device 14 according to the present embodiment is not limited as long as it ejects a gas G into the molten metal M to flow the molten metal M to generate a vortex, but it is also a jet pump whose cross section is outlined in FIG. It is desirable to adopt the configuration of the jet pump 16 referred to. The jet pump 16 pumps a high-pressure driving fluid G to the nozzle 17 and ejects the high-pressure driving fluid G toward the throat 18 at a high speed, so that the pressure of the jet becomes low, and the driven fluid M around the jet flows. Is drawn in and jetted while mixing. Therefore, if the jet pump 16 is used, by injecting the gas G as the driving fluid, the surrounding molten metal M is sucked or entrained as the driven fluid and injected together with the gas G. Therefore, only the gas G is used as the melting chamber. Rather than imparting fluidity to the molten metal M in 11, the molten metal M can be easily flowed in each stage, and a vortex can be easily generated.

In particular, as shown in FIGS. 3 and 4, the jet portion 14B is arranged between the walls between the dissolution chamber 11 and the circulation chamber 50, that is, the communication passage 51 between the dissolution chamber 11 and the circulation chamber 50 and the like. At the same time, if the configuration of the jet pump 16 is adopted, the molten metal M in the vicinity of the communication passage 51 will flow into the melting chamber 11 together with the gas G, and an eddy current can be effectively generated, and the melting raw material B and the melting raw material B can be generated. This is desirable because the contact with the ejection portion 14B, which is a part of the gas ejection device 14, is eliminated. Further, a flow of the molten metal M refluxing from the heating chamber 20 to the melting chamber 11 is generated, and the undissolved dissolved raw material B among the dissolved raw materials B supplied to the melting chamber 11 does not stay in the melting chamber 11 and enters the heating chamber 20. It is supplied so that the dissolution raw material B can be effectively dissolved.

The gas G ejected into the molten metal M is preferably an inert gas (hereinafter referred to as "inert gas") that is inactive with respect to the molten metal M such as nitrogen gas and argon gas. The generation of the inert gas G and the method of supplying air are not limited. It may be supplied by pumping from a compressor that separates nitrogen gas from air or a cylinder filled with an inert gas. It is preferable to eject at a pressure of 0.5 MPa or less, more preferably 0.3 to 0.5 MPa. By blowing the inert gas G into the molten metal M, the degassing effect is exhibited at the same time as the vortex is generated, and the molten metal M can be cleaned. In particular, the generation of a vortex increases the contact between the molten metal M and the inert gas G, so that a high degassing effect can be obtained. Further, by adopting such a configuration, it is not necessary to separately provide a degassing chamber in the melting and holding furnace 1, and the entire furnace can be made compact.

In the metal melting apparatus 10 of the embodiment shown in FIGS. 1 to 4, since a vortex of the molten metal M is generated in the melting chamber 11 by gas ejection, it is formed in the upper part of the melting chamber 11 and is charged from the supply port 11A. Among the melting raw materials B, the melting raw material B, which is lightweight like a briquette material or has a lighter specific gravity than the molten metal M and floats on the molten metal M, is drawn toward the bottom side of the center of the vortex. On the other hand, the molten material B, which has a mass and a heavier specific gravity than the molten metal M, sinks to the bottom while being caught in the vortex or receiving the vortex.
In the melting chamber 11 of this form, since the vortex is generated by the gas G instead of being generated by the dynamic mechanical device portion such as the stirring blade, even the melting raw material B having a light specific gravity sinks in the molten metal M. Since the melting raw material B does not come into contact with the mechanical device portion, there is an advantage that it can be supplied to the melting chamber 11 together with the melting raw material B having a light specific density.

Examples of the melting raw material B according to the present invention include scrap materials such as return material, briquette material and chips, and new materials. Among them, the briquette material and chips are easy to float with respect to the molten metal M, and , The return material and the new material are liable to sink with respect to the molten metal M. Therefore, in the metal melting apparatus 10 according to the embodiment shown in FIGS. 1 to 4, the briquette material and chips are rapidly drawn into the vortex bottom by the vortex flow and sent to the heating chamber 20. Further, the new material and the return material are exposed to a vortex in the process of sinking in the molten metal M, and the dissolution proceeds. Therefore, in the metal melting device 10 that generates a vortex in the melting chamber 11 by ejecting the gas G according to this embodiment, the melting chamber can be any combination of scrap materials such as return material, briquette material and chips, and a new material. There is an advantage that it can be supplied to 11. In the metal melting device 10, for example, when only the melting raw material B that sinks in the molten metal M such as a new material or a return material is dissolved, the gas ejection is stopped and the molten metal M such as chips or briquette material is formed. The gas may be ejected to generate a vortex only when the dissolved raw material B that is hard to sink is supplied.

In the melting and holding furnace 1 incorporating the metal melting device 10 according to the present invention and the metal melting device 10 according to the present invention described above, the melting raw material B having a lighter specific gravity than the molten metal M such as a briquette material is oxidized. It is possible to obtain a clean molten metal M with a small amount of oxide by dissolving it so as not to cause it.

1 ... Melting and holding furnace, 2,112 ... Refractory material, 3 ... Outer shell,
10 ... metal melting device, 20 ... heating chamber, 21 ... immersion heater (immersion burner), 22 ... heating chamber lid, 30 ... sedative chamber, 40 ... pumping chamber, 50 ... circulation chamber, 51 ... communication passage,
11,101,102 ... Melting chamber, 11A ... Supply port, 13 ... Supply path, 13A ... Melting chamber side opening, 13B ... Supply path upper wall surface,
14 ... gas ejection device, 14A ... ejection port, 14B ... ejection part, 14C ... air supply pipe, 14D ... gas generator 16 ... jet pump, 17 ... nozzle, 18 ... throat G ... inert gas / gas / driving fluid, B ... dissolution raw material, M ... molten metal / driven fluid,
70 ... screen board, 71 ... through hole,
114 ... Magnetic stirrer, 115 ... Rotating shaft, 116 ... Stirring blade.

The present invention relates to a metal melting apparatus that melts a melting raw material in a molten metal, and in particular, melts a melting raw material such as aluminum, an aluminum alloy, and a non-ferrous metal in order to prepare a molten metal for supplying to a casting machine, a melting furnace, or the like. Regarding metal melting equipment.

Due to the growing awareness of environmental protection, the automobile industry and the like are promoting the weight reduction of members and devices by various casting products such as engine blocks. Along with this, the amount of lightweight non-ferrous metal materials such as aluminum materials and aluminum alloy materials is increasing.
For this reason, efforts are being made to reduce the amount of new materials used in the raw materials by using scrap materials such as return materials, briquette materials, and chips as the melting raw materials for the molten metal that manufactures castings.

Among scrap materials, briquette material is solidified by compressing cutting chips and chips generated from processing, and contains oil and water. Therefore, if it is supplied to the molten metal as it is, the oil will burn and exhaust gas will be emitted. Since it is generated, a pretreatment for evaporating oil, water, etc. contained in advance may be performed.

However, since the briquette material has a smaller specific density and a larger surface area than the molten metal, there is a problem that even if the pretreatment is performed, the briquette material easily floats on the surface of the molten metal and a part of the briquette material is easily oxidized during melting. And, for example, as _{the melting point of Al 2} O _{3 which is an oxide of aluminum is 2072 ° C., Al 2} O ₃ which is an oxide of a non-ferrous metal material such as an aluminum material has an extremely high melting point and is in a molten metal. When _{an oxide such as Al 2} O ₃ is formed in the molten metal, it does not dissolve in the molten metal and becomes a foreign substance, which deteriorates the quality of the casting.

On the other hand, as a technique for making it difficult for oxides to be formed when the briquette material is melted into a molten metal, the briquette material is melted by supplying the briquette material to the vortex of the molten metal as described in Patent Document 1 or 2 below. There is a technique to pull in quickly.

Japanese Unexamined Patent Publication No. 2013-60629 Japanese Unexamined Patent Publication No. 2-219978

However, even if the briquette material is drawn into the molten metal by the vortex flow, the drawn briquette material may not be completely dissolved and may be transferred to the next process without being dissolved.
Then, in such a case, the undissolved briquette material floats on the surface of the molten metal in the next step and is oxidized there.

Therefore, a main object of the present invention is to provide a metal melting apparatus that solves the above-mentioned problems of the prior art and melts a melting raw material having a lighter specific gravity than a molten metal such as a briquette material so as not to oxidize.

The means for solving the above problems are as follows.

The first means is
A melting chamber that supplies the melting raw material into the molten metal,
It has a heating chamber that communicates with the melting chamber via a supply path and has a heating means for heating the molten metal.
A screen plate is provided in the heating chamber to prevent the undissolved dissolved raw material transferred from the supply path from floating until it reaches at least a predetermined size.
It is a metal melting device characterized by the above.

The second means is
The screen plate has a large number of through holes, and the through holes are tapered from the bottom surface side to the top surface side, and is a metal melting device according to the first means.

The third means is
The first or second means is provided with an impact applying means for giving an impact to the undissolved dissolved raw material transferred from the melting chamber to the heating chamber in the vicinity of the supply passage or the supply passage of the melting chamber. It is a metal melting device.

The fourth means is
The impact applying means is a metal melting device according to the third means, which is an inner wall of the supply path or an inner wall in the vicinity of the supply path of the melting chamber, which is configured so that the undissolved dissolved raw materials collide with each other. ..

The fifth means is
The metal melting apparatus according to the first to fourth means, wherein the melting chamber is provided with a vortex generating means for generating a vortex in the molten metal in the melting chamber.

The sixth means is
The metal melting apparatus according to the fifth means, wherein the vortex generating means generates a vortex in the molten metal by ejecting a gas into the molten metal.

The seventh means is
The metal melting apparatus according to the sixth means, wherein the gas is an inert gas that is inert to the molten metal.

[Action effect]
According to the present invention, in order to melt a melting raw material having a lighter specific gravity than a molten metal such as a briquette material which is a scrap material of an aluminum alloy or a non-ferrous metal material, a screen plate is provided in a heating chamber. Since the molten raw material is prevented from floating on the surface of the molten metal, it is prevented from coming into contact with air or the like on the surface of the molten metal to be oxidized, and a clean molten metal with less oxide can be obtained. Further, the yield of the molten metal to be refined is improved, and the slag treatment work for the oxide treatment is also reduced.

Further, assuming that the screen plate has a large number of through holes and the through holes have a tapered shape narrowing from the bottom surface side to the top surface side, the dissolved raw material fits into the through holes and is predetermined. It can be held until it is large enough to be dissolved before it rises to the surface of the water, and can be dissolved without floating on the surface of the water so as not to be suitably oxidized.

Further, if an impact applying means for giving an impact to the undissolved dissolved raw material transferred to the heating chamber is provided near the supply path or the supply path of the melting chamber, the undissolved dissolved raw material is impacted by the impact applying means. It is easily dissolved by the time it is crushed and supplied to the heating chamber. In particular, if it is a material such as a briquette material that is solidified by compressing cutting chips, chips, etc., it is likely to collapse due to an impact, and dissolution can proceed particularly effectively.
If the impact applying means is a supply path or the like configured so that the undissolved dissolved raw materials collide with each other, the undissolved dissolved raw materials can be impacted simply and without creating a dynamic portion.

Further, if the melting chamber is provided with a vortex generating means for generating a vortex in the molten metal in the melting chamber, even if a scrap material having a light specific density such as a briquette material is supplied, they quickly reach the bottom of the vortex at the center of the vortex. Since it is drawn in, it becomes difficult to come into contact with the outside air, so that it becomes difficult for oxides to be formed and a cleaner molten metal can be obtained.

Further, if the vortex flow generating means is to generate a vortex flow in the molten metal by ejecting a gas into the molten metal, it is possible to prevent a stirring member such as a stirring blade or a stirrer from being present at the bottom of the center of the vortex, and it can be used as a melting raw material. The risk of contact with the stirring member is reduced to each stage, and not only the melting raw materials such as briquettes and chips, which have a lighter specific gravity than the molten metal, but also the melting raw materials that sink in the molten metal such as return materials and new materials are combined into the melting chamber. It will be able to be supplied and dissolved. Since the number of dynamic parts such as stirring blades and stirrers can be reduced, maintenance and handleability will be improved.

Further, if the gas is an inert gas that is inert to the molten metal, the degassing effect is exhibited, and a cleaner and higher quality molten metal can be obtained.

According to the present invention, there is provided a metal melting apparatus that melts a melting raw material having a lighter specific gravity than a molten metal such as a briquette material so as not to oxidize.

It is a top view of the plane of the melting holding furnace including the metal melting apparatus which concerns on this invention. FIG. 1 is a view taken along the line II-II in FIG. 1, which is a schematic cross-sectional view of a melting and holding furnace including the metal melting device according to the present invention. However, for convenience of explanation, members that do not appear in the II-II arrow are also described. It is a top view of the plan view of the melting holding furnace including another metal melting apparatus which concerns on this invention. FIG. 3 is a view taken along the line IV-IV in FIG. 3, which is a schematic cross-sectional view of a melting and holding furnace including another metal melting device according to the present invention. However, for convenience of explanation, members that do not appear in the IV-IV arrow are also described. It is sectional drawing for demonstrating the jet pump which concerns on this invention. It is a perspective view for demonstrating the screen board which concerns on this embodiment. It is a VI-VI sectional view of another screen plate which concerns on this embodiment. It is a perspective view for demonstrating another screen board which concerns on this Embodiment. It is VIII-VIII sectional view of another screen plate which concerns on this embodiment. It is sectional drawing of the example of the melting chamber which concerns on this invention. It is sectional drawing of another example of the melting chamber which concerns on this invention. It is a top view of the plan of the melting holding furnace which includes another metal melting apparatus which concerns on this invention. FIG. 12 is an arrow view of XIII-XIII in FIG. 12, which is a schematic cross-sectional view of a melting and holding furnace including another metal melting device according to the present invention. However, for convenience of explanation, members and the like that do not appear in the XIII-XIII arrow are also described.

Hereinafter, embodiments according to the present invention will be described with reference to FIGS. 1 to 13.
The metal melting apparatus 10 according to the present embodiment has a melting chamber 11 for supplying the melting raw material B into the molten metal M, and a heating chamber 20 for heating the molten metal M by communicating with the melting chamber 11 via the supply path 13. ing. The metal melting apparatus 10 according to the present embodiment has a sedation chamber 30 that holds the molten metal M and precipitates impurities and the like in the molten metal M, an external casting machine that pumps out the molten metal M, and other melting and holding furnaces and holding. It is preferably incorporated in a melting and holding furnace 1 provided with a pumping chamber 40 for discharging hot water to a furnace or the like. A melting and holding furnace 1 incorporating the metal melting device 10 is also proposed as the present invention.

However, the metal melting device 10 of the present invention is not limited to the form incorporated in the melting and holding furnace 1 according to the present embodiment, and can be used alone or as a device for supplying and melting the melting raw material B into the molten metal M. It can be carried out by incorporating it into other types of melting and holding furnaces and melting furnaces.

In the melting and holding furnace 1 according to the present embodiment, each chamber is formed of a refractory material 2 in the outer shell 3, and the melting chamber 11 communicates with the heating chamber 20 via a supply path 13. Further, a circulation chamber 50 communicating with the heating chamber 20 and the melting chamber 11 is preferably provided, and the molten metal M is configured to be able to return from the heating chamber 20 to the melting chamber 11 via the circulation chamber 50.

The melting chamber 11 has a supply port 11A for supplying the melting raw material B upward, and is an aluminum or aluminum alloy which is the melting raw material B from a carry-in device such as a hopper or a conveyor (not shown) via the supply port 11A. And other non-ferrous metal materials are supplied to the molten metal M in the melting chamber 11. Specific forms of aluminum, aluminum alloys and other non-ferrous metal materials include scrap materials such as return materials, briquette materials and chips, and new materials. In particular, the metal melting apparatus 10 according to the present invention is suitable for a melting raw material B such as a briquette material which has a lighter specific gravity than the molten metal M and floats on the surface of the molten metal. The dissolved raw material B containing oil, water, etc. of the briquette material may be pretreated to remove the oil, water, etc. by drying and preheating in advance.

In the heating chamber 20, as a preferable form, immersion heaters 21 and 21 are arranged so as to be inserted into the heating chamber 20 from above to heat the molten metal M. By heating the molten metal M by the immersion heaters 21 and 21, the temperature of the molten metal M in the melting holding furnace 1 is maintained, and the melting raw material B supplied to the melting chamber 11 and the heating chamber 11 from the melting chamber 11 via the supply path 13 are used. The dissolution raw material B sent to No. 20 is dissolved in the molten metal M. However, the heating means of the molten metal M in the heating chamber 20 is not limited to the immersion heaters 21 and 21, and an immersion burner may be adopted. Further, the arrangement of the immersion heaters 21 and 21 is not limited to the form of inserting into the heating chamber 20 from above, but also the form of inserting into the heating chamber 20 from the side wall side of the heating chamber 20 as shown in FIGS. 12 and 13. It may be arranged in.

Further, the heating chamber 20 includes a melting chamber lid 22 installed by closing the upper opening so as not to create a space between the molten metal M and the surface of the molten metal M, and the melting chamber 20 is sent from the melting chamber 11. The raw material B is easily dissolved in an oxygen-free state. However, the heating chamber 20 according to the present invention does not necessarily have to be provided with a melting chamber lid 22 that does not form a space between the molten metal M and the surface of the molten metal M.

It is desirable that the outlet of the supply path 13 from the melting chamber 11 to the heating chamber 20 is located below the heating chamber 20, as shown in FIGS. 2, 4 and 13. By setting the outlet of the supply path 13 as the lower part of the heating chamber 20, for example, the melting raw material B having a lighter specific gravity than the molten metal, such as an undissolved briquette material that was not completely melted in the melting chamber 11, is heated. When supplied to the chamber 20, the molten metal M in the heating chamber 20 can be melted in the process of floating, and an event in which undissolved briquette material accumulates in the upper part of the heating chamber 20 and is oxidized is less likely to occur. .. Even if the upper opening is closed by the melting chamber lid 22 so as not to create a space between the molten metal M and the molten metal surface, a gas such as air is provided between the melting chamber lid 22 and the molten metal surface. In addition, in the dissolved raw material B containing oil and water such as briquette material, gas derived from water and oil may accumulate on the lower surface of the lid, so that the dissolved raw material B floats on the surface of the hot water. May be oxidized. Therefore, even when the upper opening is closed by the melting chamber lid 22 so as not to create a space between the molten metal and the surface of the molten metal, it is desirable that the outlet of the supply path 13 is located below the heating chamber 20. ..

In the metal melting apparatus 10 according to the present embodiment, as shown in FIGS. 2, 4 and 13, characteristically, the lower part where the outlet of the supply path 13 of the heating chamber 20 is located and the upper part above it. A screen plate 70 is provided in the heating chamber 20 to prevent the molten material B transferred from the supply path 13 from floating until it reaches at least a predetermined size.

As shown in FIGS. 6 to 8, the screen plate 70 is a plate-like body formed of a material that can be submerged and installed in the molten metal M and has a large number of through holes 71, and is a plate-like body having a large number of through holes 71, and is a supply path 13 from the melting chamber 11. The undissolved dissolved raw material B supplied into the heating chamber 20 through the screen plate 70 is placed at a position particularly below the screen plate 70 in the heating chamber 20 until it becomes large enough to pass through the through hole 71 formed in the screen plate 70. Hold it so that the dissolution proceeds in the molten metal M. However, the screen plate 70 is not limited to this, and is not particularly limited as long as it prevents the melting raw material B having a specific gravity lighter than that of the molten metal M from floating.

By providing the screen plate 70 in the heating chamber 20 in this way, it is possible to prevent the melting raw material B, which has a lighter specific gravity than the molten metal such as briquette material, from floating up to the surface of the molten metal in the heating chamber 20. It becomes possible to dissolve in anoxic state.

The number and size of the through holes 71 formed in the screen plate 70 are not particularly limited, but the size and dissolution rate of the dissolved raw material B to be supplied, the distance between the installation depth of the screen plate 70 and the molten metal surface, and the melting raw material It may be determined appropriately in consideration of the property of B and the like. The melting raw material B having a size that allows it to pass through the through hole 71 may be set so as to be sufficiently dissolved by the molten metal before it floats on the surface of the molten metal. Preferably, it is desirable to design so that the time until the undissolved dissolved raw material B floats through the through hole and is dissolved before reaching the surface of the molten metal is 2 to 3 minutes. For example, considering the general size of a briquette material from an aluminum scrap material, it is desirable that the through hole 71 has a diameter of 20 to 50 mm.

Further, it is desirable that the through hole 71 has a cylindrical shape as shown in FIGS. 6 and 7, or a tapered shape that narrows upward as shown in FIGS. 8 and 9. With this configuration, the undissolved raw material B fits into the through hole 71, stays in a fixed position without moving in the heating chamber 20, and the dissolution facilitates.

The material of the screen plate 70 may be any material that can be submerged and installed in the molten metal M, but is preferably silicon carbide, zirconia, or fine ceramics.
The thickness of the screen plate 70 is not particularly limited, but if it is the above material, it is easy to obtain sufficient strength if it is 20 to 80 mm.

The screen plate 70 may be installed in the heating chamber 20 so as to be fixed to the bottom of the heating chamber 20 or suspended from the top surface of the heating chamber 20. The installation method is not limited. However, if the immersion heaters 21 and 21 are arranged so as to be inserted into the room from above as in the heating chamber 20 of the embodiment, the screen plate 70 is provided so that the immersion heaters 21 and 21 and the floating melting raw material B do not come into contact with each other. Is preferably placed below the bottom of the immersion heaters 21 and 21. Further, the screen plate 70 is preferably provided at a height of 20 to 35% from the bottom of the heating chamber 20. Further, as shown in FIG. 4, a plurality of screen plates 70 may be provided in the heating chamber 20. In this case, the hole diameter of the through hole 71 of each screen plate 70 may be different. In that case, it is desirable that the diameter of the through hole 71 of the upper screen plate 70 be smaller than the diameter of the through hole 71 of the lower screen plate 70.

On the other hand, the metal melting apparatus 10 according to the present invention is an impact applying means for giving an impact to the undissolved dissolved raw material B sent from the melting chamber 11 to the heating chamber 20 in the vicinity of the supply passage 13 or the supply passage 13 of the melting chamber 11. It is desirable to provide. The impact applying means may dynamically apply an impact, but preferably, in terms of maintainability, the undissolved dissolved raw material B collides in the process of being conveyed to the heating chamber 20 by the flow of the molten metal. It is desirable that it is a static object such as an obstacle that does. For example, a convex portion may be provided on the inner wall of the supply path 13 or the inner wall in the vicinity of the supply path 13 of the melting chamber 11 so that the undissolved dissolved raw material B collides with the convex portion when passing through. Further, as a specific example, the undissolved dissolved raw material B such as a briquette material having a lighter specific gravity than the molten metal M is along the upper surface of the supply path 13 due to the buoyancy and the flow of the molten metal M into the heating chamber 20. As shown in FIGS. 2, 4 and 13, if the upper wall surface 13B of the supply path 13 is formed in a stepped shape or a convex portion is formed on the upper wall surface 13B, it is not possible. When the dissolution raw material B for dissolution moves to the heating chamber 20, it collides with the stepped upper wall surface 13B of the supply path 13 and the convex portion formed on the upper wall surface 13B, and an impact is applied to the undissolved dissolution material B. The raw material B collapses and is easily melted quickly in the heating chamber 20 in which the screen plate 70 is installed.

On the other hand, in the metal melting apparatus 10 according to the present invention, it is desirable that the melting chamber 11 is provided with a vortex generating means for generating a vortex in the molten metal M in the melting chamber 11. As the vortex generating means, as shown in FIGS. 1 to 4 and 12 to 13, it is desirable that the vortex is generated in the molten metal M by ejecting the gas G into the molten metal M. As shown in FIG. 10, a magnetic stirrer 114 may be provided below the melting chamber 11 to generate a vortex in the molten metal M in the melting chamber 11. Further, as shown in FIG. 11, a stirring device provided with a stirring blade 116 at the tip of the rotating shaft 115 is inserted into the molten metal M of the melting chamber 11, and the molten metal M is stirred by the stirring blade 116 to generate a vortex. It may be made like this. In this embodiment, the degassing treatment may be performed by injecting the inert gas G, which is inert to the molten metal M, from the tip of the rotating shaft 115. By generating a vortex flow in the molten metal M in the melting chamber 11 as in these forms, even if the melting raw material B having a lighter specific density than the molten metal M is supplied, they are quickly drawn into the vortex bottom at the center of the vortex. As a result, the melting raw material B and the outside air are less likely to come into contact with each other, and oxides are less likely to be formed, resulting in a cleaner molten metal M. Further, in the process in which the dissolved raw material B is agitated by the vortex flow, the collision between the dissolved raw materials B is promoted and the dissolved raw materials B are easily dissolved by the collapse. In particular, in a briquette material obtained by compressing and solidifying cutting chips and chips, collapse occurs effectively.

The shape of the melting chamber 11 may be a rectangular box shape, but if a vortex is to be generated, the shape of FIG. 1 is particularly high.
As shown in No. 4 and FIGS. 12 to 13, it is desirable that the inner space in which the molten metal M is stored is a substantially cylindrical shape or a substantially inverted conical shape. The molten metal M is flowed so as to be guided by the inner wall surface, so that a vortex of the molten metal M is likely to be generated in the melting chamber 11 and the vortex is easily maintained. Therefore, it is possible to reduce the energy related to the gas ejection.

Further, when the melting chamber 11 is to generate a vortex, the melting chamber side opening 13A of the supply path 13 connecting the melting chamber 11 and the heating chamber 20 is formed at the central bottom of the vortex, for example, FIGS. 2 and 4. And, as shown in FIG. 13, it is desirable to form it at the central bottom of the dissolution chamber 11. The dissolved raw material B is drawn into the center of the vortex bottom by the vortex flow, and the dissolved raw material B is supplied to the heating chamber 20 without floating, so that the dissolved raw material B is effectively melted.

Further, it is desirable that the melting chamber 11 is provided with a molten metal heating means for heating the molten metal M. Although not shown, the molten metal heating means may be provided with a dipping heater at the bottom of the melting chamber 11 or near the side wall. The immersion heater may be arranged so as to be inserted into the molten metal M from above near the side wall of the melting chamber 11. If the molten metal heating means is provided in the melting chamber 11, the molten metal M stored in the melting chamber 11 is heated, the temperature drop of the molten metal M due to the supply of the melting raw material B is reduced, and the melting raw material B is easily melted more quickly. Become. Further, a dipping burner may be used instead of the dipping heater.

Subsequently, as a vortex generating means which is a particularly preferable form in the melting chamber 11 according to the present invention, a specific form for generating a vortex in the molten metal M by ejecting the gas G into the molten metal will be described.
As shown in FIGS. 1 to 4, the melting chamber 11 characteristically creates a vortex in which the gas G is ejected into the molten metal M in the melting chamber 11 and the molten metal B is stirred together with the molten metal M. A gas ejection device 14 for generating gas inside is provided, and the metal melting device 10 is configured together with the heating chamber 20.

As shown in the figure, the gas ejection device 14 is, for example, an ejection portion 14B having an ejection port 14A located in the molten metal M, an air supply pipe 14C communicating with the ejection portion 14B, and a gas generator 14D for generating gas G. Can be configured. For example, when the gas is nitrogen gas, examples of the gas generator include "nitrogen gas generator (N2 pack)" manufactured by Hitachi Industrial Equipment Systems Co., Ltd. and equivalent devices manufactured by Anest Iwata Co., Ltd. By ejecting the gas G sent from the gas generator 14D into the melting chamber 11 via the air supply pipe 14C from the ejection port 14A into the molten metal M, the molten metal M in the melting chamber 11 is agitated and a vortex is generated. Let me.

Further, although not shown, a straightening vane may be provided in the melting chamber 11 to guide the gas G ejected from the ejection port 14A in an appropriate direction to facilitate the generation of a vortex flow. For example, a straightening vane protruding from the inner wall of the melting chamber 11 toward the center of the melting chamber 11 is provided at a position immediately above the ejection port 14A. The gas G ejected from the ejection port 14A becomes bubbles and does not rise immediately, so that a vortex flow is likely to occur. At this time, if the straightening vane is tilted so as to move slightly upward as the distance from the ejection port 14A side increases, the gas G is injected in a substantially spiral direction, and it becomes easier to generate a vortex flow. Further, a groove may be formed spirally on the inner wall of the melting chamber 11. In this way, eddy currents are more likely to occur.

In the gas ejection device 14 of the present embodiment, it is desirable that the ejection portion 14B is provided in the vicinity of the inner wall surface in the melting chamber 11 as shown in FIGS. 1 and 2, 12 and 13. The supplied melting raw material B is drawn to the center of the vortex flow by the vortex flow. If the ejection portion 14B is near the inner wall surface, the dissolution raw material B is less likely to come into contact with the ejection portion 14B, and the risk of damage to the gas ejection device 14 is reduced.

Further, as shown in FIGS. 3 and 4, the gas ejection device 14 is provided in the side wall of the dissolution chamber 11 so as to be less likely to come into contact with the dissolution raw material B, and the ejection port 14A is provided in the dissolution chamber 11 from the wall surface. You may try to face. In the embodiment shown in FIGS. 3 and 4, the melting chamber 11 is a part of the melting holding furnace 1, and the circulation chamber 50 and the circulation passage are provided so that the molten metal M returns from the heating chamber 20 to the melting chamber 11. Therefore, the molten metal M is circulated from the heating chamber 20 to the melting chamber 11, such as between the walls between the melting chamber 11 and the circulation chamber 50, that is, the communication passage 51 between the melting chamber 11 and the circulation chamber 50. A spouting portion 14B is provided in the road so that the spouting port 14A faces the melting chamber 11. By doing so, the ejection portion 14B is not located in the melting chamber 11, the contact between the ejection portion 14B and the dissolution raw material B is effectively prevented, and the risk of damage to the gas ejection device 14 is further reduced. ..

As shown in FIGS. 1 to 4, the desired direction of the gas G ejection port 14A, that is, the gas ejection direction, may be set so that the center of the generated vortex flow is the central portion of the melting chamber 11. For example, if the melting chamber 11 has a substantially circular diameter in a plan view as shown in the illustrated example, it may be oriented in the substantially tangential direction of the circle.

Further, as shown in FIGS. 1 and 2, FIG. 12 and FIG. 13, the ejection portion 14B is provided at a depth position near the bottom portion in the melting chamber 11, and the ejection port 14A is directed slightly upward so that the ejection port 14A is directed slightly upward. If the gas G ejected from the gas G is ejected from the side of the bottom of the dissolution chamber 11 in a spiral direction with respect to the central portion of the dissolution chamber 11, it becomes easier to generate a vortex in the dissolution chamber 11. The ejection direction of the gas G shown in the figure is an example in which the central portion of the melting chamber 11 is set to be the center of the vortex, but of course, the center of the vortex flow is set to be different from the central portion of the melting chamber 11. In this case, the ejection port 14A and the ejection portion 14B may be appropriately provided so that the gas G is ejected in the spiral direction with respect to the center of the vortex flow.

It is desirable that the number of gas G ejection points in the dissolution chamber 11 is a plurality. In the illustrated form, it is provided in two places. When there are a plurality of ejection points, one gas ejection device 14 having a plurality of ejection ports 14A may be provided in the dissolution chamber 11, or a plurality of gas ejection devices 14 may be provided in the dissolution chamber 11. Good. If the gas G is ejected from a plurality of places, a larger stirring force for the molten metal M can be generated, so that a vortex flow is likely to occur. In this case, if the ejection port 14A is arranged at a point-symmetrical position with respect to the center of the vortex to be generated, for example, the central portion of the melting chamber 11, the vortex can be more easily generated. Further, when there are a plurality of ejection points, eddy currents are more likely to occur if the depth positions of the ejection points are different. If it is a general melting chamber 11, the depth of one ejection portion is preferably 350 to 400 mm, and the other ejection portion is preferably 170 to 230 mm.

The gas ejection device 14 according to the present embodiment is not limited as long as it ejects a gas G into the molten metal M to flow the molten metal M to generate a vortex, but it is also a jet pump whose cross section is outlined in FIG. It is desirable to adopt the configuration of the jet pump 16 referred to. The jet pump 16 pumps a high-pressure driving fluid G to the nozzle 17 and ejects the high-pressure driving fluid G toward the throat 18 at a high speed, so that the pressure of the jet becomes low, and the driven fluid M around the jet flows. Is drawn in and jetted while mixing. Therefore, if the jet pump 16 is used, by injecting the gas G as the driving fluid, the surrounding molten metal M is sucked or entrained as the driven fluid and injected together with the gas G. Therefore, only the gas G is used as the melting chamber. Rather than imparting fluidity to the molten metal M in 11, the molten metal M can be easily flowed in each stage, and a vortex can be easily generated.

In particular, as shown in FIGS. 3 and 4, the jet portion 14B is arranged between the walls between the dissolution chamber 11 and the circulation chamber 50, that is, the communication passage 51 between the dissolution chamber 11 and the circulation chamber 50 and the like. At the same time, if the configuration of the jet pump 16 is adopted, the molten metal M in the vicinity of the communication passage 51 will flow into the melting chamber 11 together with the gas G, and an eddy current can be effectively generated, and the melting raw material B and the melting raw material B can be generated. This is desirable because the contact with the ejection portion 14B, which is a part of the gas ejection device 14, is eliminated. Further, a flow of the molten metal M refluxing from the heating chamber 20 to the melting chamber 11 is generated, and the undissolved dissolved raw material B among the dissolved raw materials B supplied to the melting chamber 11 does not stay in the melting chamber 11 and enters the heating chamber 20. It is supplied so that the dissolution raw material B can be effectively dissolved.

The gas G ejected into the molten metal M is preferably an inert gas (hereinafter referred to as "inert gas") that is inactive with respect to the molten metal M such as nitrogen gas and argon gas. The generation of the inert gas G and the method of supplying air are not limited. It may be supplied by pumping from a compressor that separates nitrogen gas from air or a cylinder filled with an inert gas. It is preferable to eject at a pressure of 0.5 MPa or less, more preferably 0.3 to 0.5 MPa. By blowing the inert gas G into the molten metal M, the degassing effect is exhibited at the same time as the vortex is generated, and the molten metal M can be cleaned. In particular, the generation of a vortex increases the contact between the molten metal M and the inert gas G, so that a high degassing effect can be obtained. Further, by adopting such a configuration, it is not necessary to separately provide a degassing chamber in the melting and holding furnace 1, and the entire furnace can be made compact.

In the metal melting apparatus 10 of the embodiment shown in FIGS. 1 to 4, since a vortex of the molten metal M is generated in the melting chamber 11 by gas ejection, it is formed in the upper part of the melting chamber 11 and is charged from the supply port 11A. Among the melting raw materials B, the melting raw material B, which is lightweight like a briquette material or has a lighter specific gravity than the molten metal M and floats on the molten metal M, is drawn toward the bottom side of the center of the vortex. On the other hand, the molten material B, which has a mass and a heavier specific gravity than the molten metal M, sinks to the bottom while being caught in the vortex or receiving the vortex.
In the melting chamber 11 of this form, since the vortex is generated by the gas G instead of being generated by the dynamic mechanical device portion such as the stirring blade, even the melting raw material B having a light specific gravity sinks in the molten metal M. Since the melting raw material B does not come into contact with the mechanical device portion, there is an advantage that it can be supplied to the melting chamber 11 together with the melting raw material B having a light specific density.

Examples of the melting raw material B according to the present invention include scrap materials such as return material, briquette material and chips, and new materials. Among them, the briquette material and chips are easy to float with respect to the molten metal M, and , The return material and the new material are liable to sink with respect to the molten metal M. Therefore, in the metal melting apparatus 10 according to the embodiment shown in FIGS. 1 to 4, the briquette material and chips are rapidly drawn into the vortex bottom by the vortex flow and sent to the heating chamber 20. Further, the new material and the return material are exposed to a vortex in the process of sinking in the molten metal M, and the dissolution proceeds. Therefore, in the metal melting device 10 that generates a vortex in the melting chamber 11 by ejecting the gas G according to this embodiment, the melting chamber can be any combination of scrap materials such as return material, briquette material and chips, and a new material. There is an advantage that it can be supplied to 11. In the metal melting device 10, for example, when only the melting raw material B that sinks in the molten metal M such as a new material or a return material is dissolved, the gas ejection is stopped and the molten metal M such as chips or briquette material is formed. The gas may be ejected to generate a vortex only when the dissolved raw material B that is hard to sink is supplied.

In the melting and holding furnace 1 incorporating the metal melting device 10 according to the present invention and the metal melting device 10 according to the present invention described above, the melting raw material B having a lighter specific gravity than the molten metal M such as a briquette material is oxidized. It is possible to obtain a clean molten metal M with a small amount of oxide by dissolving it so as not to cause it.

1 ... Melting and holding furnace, 2,112 ... Refractory material, 3 ... Outer shell,
10 ... metal melting device, 20 ... heating chamber, 21 ... immersion heater (immersion burner), 22 ... heating chamber lid, 30 ... sedative chamber, 40 ... pumping chamber, 50 ... circulation chamber, 51 ... communication passage,
11,101,102 ... Melting chamber, 11A ... Supply port, 13 ... Supply path, 13A ... Melting chamber side opening, 13B ... Supply path upper wall surface,
14 ... gas ejection device, 14A ... ejection port, 14B ... ejection part, 14C ... air supply pipe, 14D ... gas generator 16 ... jet pump, 17 ... nozzle, 18 ... throat G ... inert gas / gas / driving fluid, B ... dissolution raw material, M ... molten metal / driven fluid,
70 ... screen board, 71 ... through hole,
114 ... Magnetic stirrer, 115 ... Rotating shaft, 116 ... Stirring blade.

Claims (7)

A melting chamber that supplies the melting raw material into the molten metal,
It has a heating chamber that communicates with the melting chamber via a supply path and has a heating means for heating the molten metal.
A screen plate is provided in the heating chamber to prevent the undissolved dissolved raw material transferred from the supply path from floating until it reaches at least a predetermined size.
A metal melting device characterized by the fact that. The metal melting apparatus according to claim 1, wherein the screen plate has a large number of through holes, and the through holes are tapered from the bottom surface side to the upper surface side. The metal melting apparatus according to claim 1 or 2, further comprising an impact applying means for giving an impact to the undissolved dissolved raw material transferred from the melting chamber to the heating chamber in the vicinity of the supply passage or the supply passage of the melting chamber. .. The impact applying means according to any one of claims 1 to 3, wherein the impact applying means is an inner wall of the supply path configured so that the undissolved dissolved raw materials collide with each other, or an inner wall in the vicinity of the supply path of the dissolution chamber. Metal melting equipment. The metal melting apparatus according to any one of claims 1 to 4, wherein the melting chamber is provided with a vortex generating means for generating a vortex in the molten metal in the melting chamber. The metal melting apparatus according to claim 5, wherein the vortex generating means generates a vortex in the molten metal by ejecting a gas into the molten metal. The metal melting apparatus according to claim 6, wherein the gas is an inert gas that is inert to the molten metal.

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