WO2013161087A1

WO2013161087A1 - Metal melting furnace and method for generating molten metal in metal melting furnace

Info

Publication number: WO2013161087A1
Application number: PCT/JP2012/061495
Authority: WO
Inventors: 幹人笹辺; 村岡　正一
Original assignee: 有限会社ファインフォーミング
Priority date: 2012-04-28
Filing date: 2012-04-28
Publication date: 2013-10-31
Also published as: JPWO2013161087A1; JP5933696B2

Abstract

This invention is provided with: a molten metal heat retention device (100) having a first furnace wall (120) and a heater (180) capable of causing the molten metal to retain heat, the molten metal heat retention device (100) capable of housing a crucible (110) so that the opening-side outer wall surface of the crucible (110) is exposed by a predetermined amount; a crucible-fixing ring (200) having a second furnace wall (210), the inner wall surface of the second furnace wall (210) supporting, when the crucible-fixing ring (200) is in a state of being placed on the molten metal heat retention device (100), the opening-side outer wall surface of the crucible (110) in a state of being pressed against the opening-side outer wall surface along the outer circumference thereof, whereby the crucible-fixing ring (200) fixes the crucible (110); an auxiliary ring (300) having a third furnace wall (310), the auxiliary ring (300) having an inner diameter such that the inner diameter of the third furnace wall (310) is equal to or slightly larger than the outer diameter of the opening-side upper end part of the crucible (110); and a combustion device (400) having a fourth furnace wall (410) and a burner (440) for melting in the crucible (110), using a direct flame, the metal to be melted, the burner (440) being provided in a space surrounded by the fourth furnace wall (410). It is thereby possible to improve ease of maintenance, increase the lifespan, improve melting efficiency, and improve productivity of the molten metal.

Description

Metal melting furnace and molten metal generation method in metal melting furnace

The present invention relates to a metal melting furnace and a molten metal generation method in the metal melting furnace.

[Technology that promotes the reduction of carbon dioxide emissions from the viewpoint of preventing global warming has been proposed in various fields. Even in a metal melting furnace that melts a metal to produce a molten metal, there is a so-called hybrid type metal melting furnace that uses electric energy in order to suppress the use of fossil fuels such as gas as much as possible (see, for example, Patent Document 1). .)

The metal melting furnace disclosed in Patent Document 1 is a hybrid type metal melting furnace that uses a gas burner with high thermal efficiency for melting metal and uses an electric heater to keep the molten metal produced by melting.

FIG. 11 is a diagram for explaining the metal melting furnace 900 disclosed in Patent Document 1. A metal melting furnace 900 disclosed in Patent Document 1 (hereinafter sometimes simply referred to as “metal melting furnace 900”) was filed by the applicant of the present invention and is shown in FIG. In addition, a molten metal heat retaining device 910 and a combustion device 930 are provided. The molten metal heat retaining device 910 includes a crucible 911 and a crucible storage housing 912 that stores the crucible 911.

The crucible storage casing 912 has a double wall structure including a heat-resistant wall 913 made of a heat-resistant member and a heat-insulating wall 914 made of a heat-insulating member. In addition, a plurality of belt-like heaters (referred to as electric heaters) 915 are provided on the inner wall surface of the heat-resistant wall 913 so as to go around the inner wall surface.

In addition, a lid 916 is provided at the upper end of the crucible housing 912 so as to surround the outer periphery of the end of the crucible 911 on the opening side. The lid 916 has a function of maintaining the hermeticity of the thermal storage room 917. Providing such a lid 916 can enhance the heat retention effect of the thermal insulation chamber 917, and when the burner 934 of the combustion device 930 is operating, the combustion heat and combustion gas generated by the burner 934 are retained in the thermal insulation chamber 917. Can be prevented.

The combustion device 930 includes a combustion device housing 931 and a burner 934 provided at the upper end of the combustion device housing 931. The combustion device 930 is detachable from the molten metal heat retaining device 910. .

The combustion apparatus housing 931 has a double wall structure including a heat resistant wall 932 made of a heat resistant member and a heat insulating wall 933 made of a heat insulating member. When the combustion device 930 is attached to the molten metal heat retention device 910 (the state shown in FIG. 11), a combustion chamber 935 is formed between the heat resistant wall 932 and the opening of the crucible 911.

The burner 934 melts the metal 950 to be melted such as aluminum put in the crucible 110 by direct fire, and takes in, for example, LPG (liquefied propane gas) from the fuel supply pipe 936 as fossil fuel and is necessary for combustion. Air is taken in from the air intake port 937 and a flame is fired from the nozzle 938.

Also, a heat-resistant sealing material 940 made of a heat insulating material is provided between the combustion device casing 931 and the crucible storage casing 912. The heat-resistant sealing material 940 is used for closely attaching the combustion device 930 to the lid 916 provided in the crucible housing 912 when the combustion device 930 is attached to the molten metal heat retention device 910. .

By providing such a heat-resistant sealing material 940, the sealing property of the combustion chamber 935 of the combustion device 930 can be improved. Thereby, since the combustion heat of the burner 934 can be prevented from escaping to the outside, the thermal efficiency when melting the metal 950 to be melted can be increased. In addition, the effect of preventing the combustion heat and combustion gas of the burner 934 from flowing into the thermal storage room 917 can be further enhanced.

The metal melting furnace 900 configured in this way is a hybrid type metal melting furnace using a burner 934 with high thermal efficiency for melting the melted metal 950 and using an electric heater 915 for keeping the generated molten metal warm. Therefore, compared with a metal melting furnace that uses only a gas burner to perform melting and heat retention, the carbon dioxide emission can be greatly reduced. The metal melting furnace 900 is a so-called crucible melting furnace using a “crucible”. Unlike a continuous melting furnace, a crucible melting furnace is one in which a metal to be melted is placed in a crucible and the crucible is heated to generate a molten metal. For this reason, although it is not suitable for mass production like a continuous melting furnace, it can appropriately perform impurity removal work by an impurity removing device or the like, and is a metal melting furnace suitable for high-quality, high-mix, low-volume production.

Also, the metal melting furnace 900 is characterized by higher melting efficiency than a metal melting furnace using only gas. That is, in a metal melting furnace using only gas, in the initial stage of melting when melting the melted metal 950, the flame of the gas enters the gaps between the melted metals 950, and the melted metal 950 is efficiently melted. However, when the melting progresses and the molten metal is generated, the gas flame hits only the surface of the molten metal, and there is a problem that heat is hardly transmitted to the inside of the crucible 911. is there.

In contrast, the metal melting furnace 900 has high melting efficiency because the crucible 911 is heated by the electric heater 915. This is because the electric heater 915 has not only a function of keeping the molten metal at a constant temperature but also a function of speeding up melting. Further, by using the electric heater 915 as a heat source for keeping the crucible 911, it is possible to control the temperature with high accuracy and to maintain the temperature of the molten metal appropriately.

JP 2011-117640 A

As described above, the metal melting furnace 900 has excellent characteristics, but can be made a more excellent metal melting furnace by further improvement.

For example, as shown in FIG. 11, the metal melting furnace 900 is roughly divided into two structures, a molten metal heat retaining device 910 having a crucible 911 and a combustion device 930 having a burner 934, and these molten metal heat retaining devices 910. And the combustion device 930 can be divided, and the melted metal 950 in the crucible 911 is melted in a state where the combustion device 930 is placed on the molten metal heat retaining device 910.

In the metal melting furnace 900 having such a structure, the weight of the combustion device 930 is also added to the crucible 911. With such a structure, the crucible 911 may be damaged. That is, the crucible 911 is generally a so-called grilled product obtained by compressing and firing graphite, and thus is easily damaged, and preferably has a structure in which a large weight is not directly applied to the crucible 911.

Further, in the metal melting furnace 900, the combustion device 930 is a portion exposed to a high temperature, and thus the combustion device 930 has a sufficient heat-resistant structure. However, the metal to be melted 950 before melting is also used in the combustion device 930. The flame of the burner 934 directly hits the upper end portion (the portion protruding from the crucible 911). For this reason, in the combustion device 930, the area around the nozzle 938 of the burner 934 is particularly likely to be a high temperature, and is easily damaged by heat. If the damage has progressed, partial repair may be required.

In the metal melting furnace 900, the molten metal heat retaining device 910 and the combustion device 930 can be divided, but the combustion device 930 is a single structure. For this reason, even if a very narrow range of the combustion apparatus 930 is damaged by heat, the entire combustion apparatus 930 may be removed and repaired, or the entire combustion apparatus 930 may have to be recreated depending on the situation. If the entire combustion device 930 is remade, it takes a lot of days and costs, and during that time, the operation may be stopped.

Further, as described above, since the metal melting furnace 900 is composed of two components, that is, the molten metal heat retaining device 910 having the crucible 911 and the combustion device 930 having the burner 934, in the melting preparation step at the time of melting. The metal 950 to be melted is stored in the crucible 911 with the combustion device 930 removed from the molten metal heat retaining device 910.

At this time, in order to increase the production efficiency of the molten metal, in order to generate more molten metal in one melting operation, the molten metal 950 is generally stored so as to protrude from the upper opening of the crucible 911. It is. At this time, protrusion of the melted metal 950 in the vertical direction (direction along the z-axis) is allowed to some extent, but the protrusion in the horizontal direction (direction along the xy plane) is largely restricted.

This is because when the metal 950 to be melted is stored in the crucible 911 and the combustion device 930 is placed on the molten metal heat retaining device 910, the metal to be melted 950 is placed in the horizontal direction (xy) from the opening of the crucible 911. This is because if the protrusion exceeds a predetermined amount in the direction along the plane), the protruding portion becomes an obstacle and the combustion device 930 cannot be placed on the molten metal heat retention device 910.

Therefore, the operation of storing the metal 950 to be melted in the crucible 911 always takes into account that “the metal 950 to be melted is stored in the crucible 911 so that the combustion device 930 can be placed on the molten metal heat retaining device 910”. The metal 950 needs to be stored in the crucible 911. For this reason, the workability at the time of accommodating the to-be-dissolved metal 950 is bad, and there exists a subject that the accommodation amount of the to-be-dissolved metal 950 must be made small rather than the capacity | capacitance of the crucible 911 after all. For this reason, the capacity | capacitance of the crucible 911 cannot fully be utilized, but it will lead to the fall of productivity of a molten metal.

Therefore, the present invention aims to provide a metal melting furnace and a method for generating a molten metal in the metal melting furnace that can improve maintenance efficiency and extend the life, improve melting efficiency and improve molten metal productivity. To do.

[1] A metal melting furnace according to the present invention is a metal melting furnace provided with a crucible for holding a molten metal charged and holding a molten metal in which the molten metal is melted in a state of being kept warm. A first furnace wall in the shape of a bottomed container having a height; and a heater provided on an inner wall surface of the first furnace wall to keep the molten metal warm, the crucible being an opening-side outer wall surface of the crucible Has a molten metal heat retaining device that is stored so as to be exposed from the upper surface of the first furnace wall by a predetermined amount, and a ring-shaped second furnace wall that can be detachably mounted on the molten metal heat retaining device, and the molten metal heat retaining device. A crucible fixing ring for fixing the crucible by supporting an inner wall surface of the second furnace wall in a press-contact state along an outer periphery of an outer wall surface on the opening side of the crucible, and the crucible fixing Ring-shaped first that can be detachably mounted on the ring An auxiliary ring having a furnace wall, the inner diameter of the third furnace wall being the same as or slightly larger than the outer diameter of the opening side end of the crucible, and detachably mounted on the auxiliary ring; A fourth furnace wall having a height lower than the height of the first furnace wall in the vertical direction and having a predetermined space in the center, and a melting target provided in the space and charged into the crucible And a combustion device having a burner for melting the metal with an open flame.

The metal melting furnace of the present invention has a four-layer structure in which each structure of a molten metal heat retaining device, a crucible fixing ring, an auxiliary ring, and a combustion device is stacked, and each of these structures can be separated. It has become. Thus, the metal melting furnace of the present invention has a more fragmented structure as compared to the metal melting furnace 900 disclosed in Patent Document 1. For this reason, it is possible to facilitate repair or replacement work when it is necessary to repair or replace a certain structure among these structures.
In addition, the 1st furnace wall, the 2nd furnace wall, the 3rd furnace wall, and the 4th furnace wall are each formed with the heat-resistant and heat insulating member (refer to embodiment mentioned later for details).

In particular, in this type of metal melting furnace, the periphery of the combustion apparatus is exposed to high temperatures, and is easily damaged by heat. In the metal melting furnace of the present invention, the portion that is easily exposed to a high temperature has two structures, a combustion device and an auxiliary ring, which can be divided individually. For this reason, when damage due to heat progresses and repair or replacement becomes necessary, only the structure that needs repair or replacement can be taken out and repaired or replaced. For example, when the auxiliary ring is damaged, only the auxiliary ring needs to be repaired or replaced, so that maintainability can be improved.

In this way, by subdividing the metal melting furnace, it is relatively easy to prepare substitutes for individual structures, thereby eliminating the need to shut down the operation for a long period of time. Will not cause any trouble.

The metal melting furnace of the present invention is a hybrid type metal melting furnace. For this reason, according to the metal melting furnace of the present invention, when the metal to be melted is melted, the metal to be melted is melted by an open flame with a burner, and the temperature of the molten metal generated by the melting is kept by a heater. it can. In addition, since the heater has not only a function of keeping the molten metal warm, but also a function of accelerating melting, it is possible to reduce carbon dioxide emissions while enabling efficient molten metal generation.

Further, in the metal melting furnace of the present invention, the combustion chamber and the storage chamber are not the same, and each is an independent space, so that the heater is not exposed to the combustion heat or combustion gas of the burner, and the combustion heat or combustion Deterioration of the heater due to gas can be prevented, and the effect that the life of the heater can be extended is also obtained.

In the metal melting furnace of the present invention, the inner diameter of the third furnace wall in the auxiliary ring is equal to or slightly larger than the outer diameter of the upper end portion on the opening side of the crucible. With the auxiliary ring having such a structure, the weight of the auxiliary ring is not applied to the crucible when the auxiliary ring is placed on the crucible fixing ring. That is, the crucible fixing ring fixes the crucible by supporting the crucible opening-side outer wall surface in a press-contact state along the outer periphery of the opening-side outer wall surface, and thus mounting the auxiliary ring on the crucible fixing ring. Even if it is placed, the weight of the auxiliary ring is not added to the crucible. As a result, the crucible can be prevented from being damaged due to a large weight being applied to the crucible, and the crucible can have a long life.
As described above, according to the present invention, it is possible to provide a metal melting furnace capable of improving maintainability and extending the life, improving melting efficiency and improving molten metal productivity.

[2] According to the metal melting furnace of the present invention, a predetermined gap is formed between the inner wall surface of the second furnace wall and the outer wall surface on the opening side of the crucible in the crucible fixing ring. It is preferable that a crucible fixing seal made of a heat-resistant member is embedded so as to go around the outer wall surface on the opening side of the crucible.

Because of such a structure, the outer wall surface on the opening side of the crucible is surely supported by the crucible fixing ring via the crucible fixing seal. For this reason, it is possible to prevent the combustion heat and combustion gas of the burner from entering the heat retaining chamber. As a result, the heater is not exposed to the combustion heat or combustion gas of the burner, the deterioration of the heater due to the combustion heat or combustion gas can be prevented, and the life of the heater can be extended.

[3] In the metal melting furnace of the present invention, the inner wall surface of the second furnace wall may be an inclined surface such that the gap becomes narrower from the upper surface to the lower surface of the second furnace wall. preferable.

Because of this structure, the cross-sectional shape of the crucible fixing seal embedded in the gap formed between the crucible's opening-side outer wall surface is a “wedge shape” with a narrow lower portion. As a result, due to the weight of the auxiliary ring and combustion device placed on the crucible fixing ring, the horizontal pressing force (the force pressing the crucible opening side outer wall surface) due to the downward movement of the crucible fixing seal. ) Works, the adhesion between the crucible fixing ring and the crucible can be further enhanced. As a result, the effect of preventing the burner's combustion heat and combustion gas from entering the heat retaining chamber can be further enhanced.

[4] In the metal melting furnace of the present invention, a ring shape made of a heat-resistant member is provided between the lower surface of the second furnace wall in the crucible fixing ring and the upper surface of the first furnace wall in the molten metal heat retaining device. It is preferable that the molten metal heat insulation device seal is laid over the entire upper surface of the first furnace wall.

By adopting such a structure, the crucible fixing ring and the molten metal heat-retaining device can be brought into close contact with each other, so that the hermeticity of the heat retention chamber can be increased. That is, when the crucible fixing ring is placed in a state where such a molten metal heat insulating device seal is laid on the upper surface of the first furnace wall, the molten metal heat insulating device seal is pressed by the weight of the crucible fixing ring. Even if the second furnace wall in the fixing ring and the upper surface of the first furnace wall in the molten metal heat retaining device are not mirror surfaces and have some “roughness” or some unevenness, these “roughness” and unevennesses The crucible fixing ring and the molten metal heat retaining device can be brought into close contact with each other.

[5] In the metal melting furnace of the present invention, the first furnace wall is housed in a metal case, and when the first furnace wall is housed in the metal case, the upper end side of the metal case is A protruding wall is formed by slightly protruding from the upper surface of the first furnace wall, and the molten metal heat insulating device seal has an upper surface of the first electric furnace wall so that an outer periphery of the molten metal heat insulating device seal is along the protruding wall. It is preferable that it is laid.

By adopting such a structure, the protruding wall of the metal case serves to guide the laying of the molten metal heat insulation device seal, and to prevent the positional deviation after the laying is performed. Can be appropriately performed, and the molten metal heat insulating device seal can be prevented from being displaced horizontally on the first furnace wall. That is, when the molten metal heat insulating device seal is laid on the upper surface of the first furnace wall, the outer peripheral surface of the molten metal heat insulating device seal is in contact with the inner peripheral surface of the protruding wall of the metal case. The movement in the horizontal direction is restricted, thereby preventing the molten metal heat insulating device seal from being displaced in the horizontal direction.

[6] In the metal melting furnace of the present invention, a ring shape made of a heat resistant member is provided between the upper surface of the second furnace wall in the crucible fixing ring and the lower surface of the third furnace wall in the auxiliary ring. It is preferable that an auxiliary ring seal is laid, and the auxiliary ring seal is laid over the entire circumference of the upper surface of the second furnace wall.

By adopting such a structure, the crucible fixing ring and the auxiliary ring can be brought into close contact with each other, so that the degree of sealing of the space (combustion chamber) surrounded by the auxiliary ring can be increased. Also in this case, when the auxiliary ring is placed with the auxiliary ring seal laid on the upper surface of the crucible fixing ring, the auxiliary ring seal is pressed by the weight of the auxiliary ring. Even if the lower surface of the ring is not a mirror surface and has some "roughness" or some unevenness, it absorbs these "roughness" and unevenness to bring the crucible fixing ring and auxiliary ring into close contact with each other. can do.

[7] In the metal melting furnace of the present invention, between the upper surface of the second furnace wall of the crucible fixing ring and the lower surface of the third furnace wall of the auxiliary ring, the outer diameter of the auxiliary ring seal is A ring-shaped auxiliary ring seal receiving plate having an opening having the same inner diameter is laid, and the auxiliary ring seal is laid on the edge of the opening of the auxiliary ring seal receiving plate. An auxiliary ring seal guide wall is formed along an edge of the opening, the auxiliary ring seal guide wall having a height lower than a thickness dimension of the auxiliary ring seal, It is preferable that the auxiliary ring seal is laid on the upper surface of the second furnace wall of the crucible fixing ring so that the outer periphery of the auxiliary ring seal is along the inner periphery of the auxiliary ring seal guide wall.

By providing such an auxiliary ring seal receiving plate, the auxiliary ring seal receiving plate serves to guide the laying of the auxiliary ring seal and to prevent the positional deviation after laying. Positioning at the time of laying can be performed appropriately, and the auxiliary ring seal can be prevented from shifting in the horizontal direction on the crucible fixing ring.

[8] In the metal melting furnace of the present invention, a ring-shaped combustion made of a heat-resistant member is provided between the upper surface of the third furnace wall in the auxiliary ring and the lower surface of the fourth furnace wall in the combustion device. It is preferable that an apparatus seal is laid, and the combustion apparatus seal is laid over the entire circumference of the upper surface of the third furnace wall.

By adopting such a structure, the auxiliary ring and the combustion device can be brought into close contact with each other, so that the degree of sealing of the space (combustion chamber) surrounded by the auxiliary ring can be increased. Also in this case, when the combustion device is placed with the combustion auxiliary ring seal laid on the upper surface of the auxiliary ring, the auxiliary ring seal is pressed by the weight of the combustion device. Even if there is some “roughness” or some unevenness on the bottom surface, the auxiliary ring and the combustion device can be brought into close contact with each other by absorbing these “roughness” and unevenness.

[9] In the metal melting furnace of the present invention, the outer diameter of the combustion device seal is equivalent to the space between the upper surface of the third furnace wall of the auxiliary ring and the lower surface of the fourth furnace wall of the combustion device. A ring-shaped combustion device seal receiving plate having an opening having an inner diameter is laid, and an edge of the opening of the combustion device seal receiving plate is used to guide the laying of the combustion device seal. A combustion device seal guide wall is formed along an edge of the opening, the combustion device seal guide wall has a height lower than a thickness dimension of the combustion device seal, and the combustion device seal It is preferable that the outer periphery of the combustion apparatus seal is laid on the upper surface of the third furnace wall so as to follow the inner periphery of the combustion apparatus seal guide wall.

By providing such a combustion device seal receiving plate, the combustion device seal receiving plate serves to guide the laying of the combustion device seal and to prevent positional displacement after laying. Positioning at the time of laying can be performed appropriately, and the combustion apparatus seal can be prevented from shifting horizontally on the auxiliary ring.

[10] The metal melting furnace of the present invention preferably includes a crucible upper temperature sensor for detecting the temperature of the opening-side outer wall surface of the crucible.

Thereby, the temperature of the upper part (opening side outer wall surface) of the outer wall surface of the crucible can be measured. In this case, although the temperature of the molten metal inside the crucible is not directly measured, the temperature of the upper molten metal in the crucible can be estimated based on the measurement result by the crucible upper temperature sensor, and based on the measurement result. In addition, by controlling the heater and the like, it is possible to appropriately manage the temperature of the molten metal.

[11] The metal melting furnace of the present invention is characterized by having a crucible bottom temperature sensor for detecting the temperature of the bottom outer wall surface of the crucible.

This makes it possible to measure the temperature of the outer wall surface of the bottom of the crucible. Also in this case, the temperature of the molten metal inside the crucible is not directly measured, but the temperature of the molten metal in the lower part in the crucible can be estimated based on the measurement result by the temperature sensor at the bottom of the crucible. Based on the control of the heater or the like, the temperature management of the molten metal can be appropriately performed. In addition, based on the measurement result by the said crucible bottom part temperature sensor and the measurement result by the crucible top temperature sensor, temperature control etc. of a molten metal can be performed more appropriately by controlling a heater etc.

[12] The metal melting furnace of the present invention preferably has a molten metal temperature sensor that detects the temperature of the molten metal held in the crucible.

Thereby, the temperature of the molten metal held in the crucible can be directly measured, and the degree of melting of the metal to be melted in the crucible can be appropriately known based on the measurement result by the molten metal temperature sensor.

[13] In the metal melting furnace of the present invention, the heater is preferably an electric heater.

By using an electric heater as the heater, when the molten metal is heated and kept warm, the electric heater does not become a direct emission source of carbon dioxide, which can greatly contribute to the reduction of carbon dioxide emission. In addition, since the electric heater is easy to control and can be finely adjusted, the temperature of the molten metal can be controlled with high accuracy when the molten metal is heated and kept warm.

[14] The metal melting furnace of the present invention further includes an impurity removing device that can be immersed in the molten metal held in the crucible with at least the combustion device removed from the combustion device and the auxiliary ring. Is preferred.

By providing such an impurity removing device, impurities such as hydrogen gas contained in the molten metal in the crucible can be removed, and the molten metal can be made of high quality. Also, the impurity removal process can be repeated until the required quality standard is reached. Thereby, the impurity in a molten metal can be removed reliably.

[15] In the metal melting furnace of the present invention, the impurity removing device has a rotating body at the tip, and the rotating body rotates in the molten metal to generate an inert gas that is microbubbled. A degassing device of the type is preferred.

This impurity removing device generates an inert gas that has been made into microbubbles in the molten metal while the rotating body rotates, and causes the impurities to adhere to the microbubbles and float. By using such an impurity removing device, impurities such as hydrogen gas can be efficiently removed, so that a high-quality molten metal can be generated.

[16] A method for producing a molten metal in a metal melting furnace of the present invention is a method for producing a molten metal in a metal melting furnace using the metal melting furnace according to any one of [1] to [15], wherein the metal to be melted is used. Holding the molten metal to be charged into the crucible, the melting step of melting the molten metal by an open flame by the burner of the combustion device, and holding the molten metal inside the crucible at a predetermined temperature by the heater And a molten metal heat-retaining step.

As described above, the molten metal generation method in the metal melting furnace of the present invention is to perform molten metal generation using the metal melting furnace according to any one of [1] to [15]. When performing molten metal generation using such a metal melting furnace, the molten metal charging step, the melting step of attaching the combustion device to the molten metal heat retaining device to melt the molten metal, and the molten metal in the crucible were kept warm. The molten metal heat retention process held in the state is performed in this order. By performing such a process, efficient molten metal production | generation is enabled. In addition, since the metal melting furnace according to any one of [1] to [15] is used, the same effect as that of the metal melting furnace according to any one of [1] to [15] is obtained.

[17] In the molten metal production method in the metal melting furnace of the present invention, in the melting step, the molten metal is heated by the heater while melting the molten metal by an open flame with the burner. If the temperature of the predetermined portion of the crucible reaches the first set temperature, the process proceeds to the “melting / heating process using a burner / heater”, and the “melting / heating process using a burner / heater”. When the temperature of the predetermined portion of the crucible reaches a second set temperature higher than the first set temperature, it is preferable to shift from the “melting / heating process using a burner / heater together” to the molten metal heat retaining process.

By performing such a process, it is possible to significantly suppress the fuel consumption and the melting time required for melting the metal to be melted and melting it.

[18] In the molten metal production method in the metal melting furnace of the present invention, it is preferable to further include an impurity removal step of removing impurities contained in the molten metal.

By providing such an impurity removal step, impurities such as hydrogen gas contained in the molten metal can be removed, and the molten metal can be of high quality.

[19] In the molten metal production method in the metal melting furnace of the present invention, n (n is an integer of 2 or more) preparations of molten metal heat retaining devices with a crucible fixing ring in a state where the crucible fixing ring is placed on the molten metal heat retaining device. In addition, when each of the auxiliary ring and the combustion device is prepared, and the molten metal heat retaining devices with the n crucible fixing rings are used as the first to nth molten metal heat retaining devices, the first The auxiliary auxiliary ring and the combustion device are placed on the molten metal heat retaining device with the first crucible fixing ring among the molten metal heat retaining devices with the nth crucible fixing ring, and the molten metal heat retaining device with the first crucible fixing ring. It is preferable to perform the melted metal charging step, the melting step, and the molten metal heat retaining step in order to perform the molten metal heat retaining device with the nth crucible fixing ring in order.

By doing so, even in the crucible melting furnace as in the present invention, it is possible to perform a continuous molten metal production operation and a molten metal pumping operation in the same manner as the continuous melting furnace. High productivity can be obtained.

It is a perspective view showing the appearance of metal melting furnace 10 concerning an embodiment. FIG. 2 is a cross-sectional view taken along line AA of the metal melting furnace 10 in FIG. 1. It is a figure which expands and shows a part of crucible fixing ring 200 and the opening side upper end part of the crucible 110. FIG. It is a figure which takes out and shows auxiliary ring seal receiving plate 360. It is a figure shown in order to demonstrate each process of the molten metal production | generation method at the time of producing | generating a molten metal using the metal melting furnace 10 which concerns on embodiment. It is a figure shown in order to demonstrate each process of the molten metal production | generation method at the time of producing | generating a molten metal using the metal melting furnace 10 which concerns on embodiment. It is a figure shown in order to demonstrate each process of the molten metal production | generation method at the time of producing | generating a molten metal using the metal melting furnace 10 which concerns on embodiment. It is a figure shown in order to demonstrate the melting efficiency at the time of actually melt | dissolving the to-be-melted metal 600 using the metal melting furnace 10 which concerns on embodiment. It is a figure which shows the other example of the molten metal production | generation method in the metal melting furnace 10 which concerns on embodiment. It is a figure shown in order to demonstrate the modification of the installation location of the temperature sensor insertion hole 340 for measuring the temperature of a molten metal. It is a figure shown in order to demonstrate the metal melting furnace 900 currently disclosed by patent document 1. FIG.

Hereinafter, embodiments of the present invention will be described.
Drawing 1 is a perspective view showing the appearance of the metal melting furnace concerning an embodiment. The metal melting furnace 10 according to the embodiment includes a molten metal heat retaining device 100, a crucible fixing ring 200, an auxiliary ring 300, a combustion device 400, and a rotary degassing device 500.

In the metal melting furnace 10 according to the embodiment, the “metal melting furnace 10” includes the molten metal heat retaining device 100, the crucible fixing ring 200, the auxiliary ring 300, the combustion device 400, and the rotary degassing device 500. When the four components of the molten metal heat retaining device 100 excluding the degassing device 500, the crucible fixing ring 200, the auxiliary ring 300, and the combustion device 400 are described, they are collectively described as the “melting furnace body 10A”.

FIG. 2 is a cross-sectional view taken along line AA of the melting furnace main body 10A in FIG. The structure of the metal melting furnace 10 according to the embodiment will be described in detail with reference to FIGS.

The molten metal heat retaining device 100 includes a crucible 110, a first furnace wall 120 made of a heat-resistant and heat-insulating member, and a metal case 130 surrounding the first furnace wall 120.

The first furnace wall 120 has a bottomed container shape having a predetermined height in the vertical direction, and includes a heat resistant wall 121 and a heat insulating wall 122 provided outside the heat resistant wall 121. The heat resistant wall 121 is made of a heat resistant member such as a heat resistant brick, and the heat insulating wall 122 is made of a heat insulating member such as ceramic.

The crucible 110 is housed inside the first furnace wall 120 configured as described above, and a warming chamber 150 is formed between the inner wall surface of the first furnace wall 120, that is, the inner wall surface of the heat-resistant wall 121 and the crucible 110. Is done. In addition, a crucible installation table 160 for placing the crucible 110 is provided at the center of the bottom surface of the inner wall surface of the heat-resistant wall 121.

The crucible 110 is a so-called ceramic product obtained by compressing and firing graphite. The crucible 110 is installed on a crucible installation table 160 via a heat-resistant sheet 170 such as a ceramic blanket. A temperature sensor (referred to as a crucible bottom temperature sensor) TS1 capable of measuring the temperature of the bottom outer wall surface of the crucible 110 is provided on the bottom outer wall surface of the crucible 110.

The crucible bottom temperature sensor TS1 is arranged along the bottom surface of the heat-resistant wall 121 from the outside of the molten metal heat retaining device 100, and then the middle portion is bent at an angle of 90 degrees so as to follow the side surface of the crucible installation table 160. After that, the tip portion is bent at an angle of 90 degrees, and the bent tip portion (referred to as the tip bent portion P1) is arranged along the upper surface of the crucible installation base 160. And the front end bending part P1 of the crucible bottom part temperature sensor TS1 is arrange | positioned so that it may be pinched | interposed between the heat resistant sheet 170 and the lower surface side outer wall surface of the crucible 110. Note that the bending length of the tip bending portion P1 of the crucible bottom temperature sensor TS1 is about several tens of millimeters.

In this way, the bent end portion P1 of the crucible bottom temperature sensor TS1 is sandwiched between the outer wall surface on the lower surface side of the crucible 110 and the heat-resistant sheet 170, so that the bent end portion P1 is on the lower surface side of the crucible 110. It is in close contact with the outer wall surface, and the temperature of the outer wall surface on the lower surface side of the crucible 110 can be measured with high accuracy.

By the way, the surface formed by the upper surface of the heat-resistant wall 121 and the upper surface of the heat insulating wall 122 in the molten metal heat retaining device 100 (this surface may be referred to as the upper surface of the first furnace wall 120) is generally the same. Although it is a flat surface, there are some irregularities due to roughness of the heat-resistant wall 121 and the heat-insulating wall 122 instead of a mirror surface. The crucible 110 has an opening-side end portion 110a of the crucible 110 in the vertical direction of the crucible fixing ring 200 with respect to the upper surface of the first furnace wall 120 so that the opening-side outer wall surface of the crucible 110 is exposed by a predetermined amount. It is installed in the molten metal heat retaining apparatus 100 in a state of projecting upward by an amount corresponding to the height (height along the z-axis) h1.

In addition, a belt-like heater (referred to as an electric heater) 180 is provided on the inner wall surface of the first furnace wall 120, that is, the inner wall surface of the heat-resistant wall 121, so as to make a round along the inner wall surface. A plurality of electric heaters 180 are provided at predetermined intervals in the vertical direction on the inner wall surface of the heat-resistant wall 121 so that the entire crucible 110 can be uniformly heated and kept warm. In the metal melting furnace 10 according to the embodiment, four electric heaters 180 are provided.

Since the electric heater 180 heats and keeps the molten metal in the crucible 110 by radiant heat, it is said that thermal efficiency is provided as close as possible to the crucible 110 so that the crucible 110 and the electric heater 180 do not contact each other. This is preferable. However, when the crucible 110 is replaced, it is also necessary to provide an interval so that the crucible 110 does not contact the electric heater 180 when the crucible 110 is taken out from the molten metal heat insulating device 100.

The metal case 130 is formed of iron or the like, and the external shape is a bottomed cylindrical shape. The metal case 130 is formed with a flange 131 protruding in the horizontal direction along the outer periphery of the metal case 130 at the upper end of the outer peripheral surface. Moreover, the guide part insertion hole (not shown) for inserting the guide pin GP is provided in the collar part 131, for example in four places at equal intervals.

Further, on the outer peripheral surface of the metal case 130, hooks 133 (see FIG. 1) used when the molten metal heat retaining device 100 is lifted by a crane or the like are provided at, for example, four locations at equal intervals.

Further, a ring-shaped molten metal heat insulation device seal 190 is provided on the upper surface of the first furnace wall 120. The molten metal heat insulating device seal 190 is used to bring the crucible fixing ring 200 and the molten metal heat insulating device 100 into close contact with each other when the crucible fixing ring 200 is placed on the molten metal heat insulating device 100. It is almost the same as the inner diameter of. The material of the molten metal heat insulation device seal 190 is not particularly limited as long as it is a material excellent in heat resistance, airtightness and cushioning properties, but a ceramic rope or the like can be preferably used.

Further, a step slightly lower than the thickness dimension of the molten metal heat insulation device seal 190 is provided between the upper end portion of the metal case 130 (the upper surface of the flange portion 131) and the upper surface of the first furnace wall 120. By providing such a step, the upper end portion of the metal case 130 becomes a protruding wall, so that the protruding wall serves to guide the laying of the molten metal heat insulation device seal and to prevent the positional deviation after laying. Eggplant.

By providing such a step, it is possible to appropriately perform positioning when laying the molten metal heat insulation device seal 190, and it is possible to prevent the molten metal heat insulation device seal 190 from being displaced in the horizontal direction on the first furnace wall 120. . That is, when the molten metal heat insulating device seal 190 is laid on the upper surface of the first furnace wall 120, the outer peripheral surface of the molten metal heat insulating device seal 190 is in contact with the inner peripheral surface of the protruding wall of the metal case 130. The movement of the molten metal heat insulator seal 190 on the xy plane is restricted, so that the molten metal heat insulator seal 190 can be prevented from shifting on the xy plane.

As described above, when the crucible fixing ring 200 is placed on the molten metal heat retaining device 100 in a state where the molten metal heat insulating device seal 190 is laid on the upper surface of the first furnace wall 120, the molten metal heat insulating device seal 190 depends on the weight of the crucible fixing ring 200. It will be in the pressed state. For this reason, the upper surface of the first furnace wall 120 (the upper surfaces of the heat-resistant wall 121 and the heat-insulating wall 122) and the lower surface of the crucible fixing ring 200 are not mirror surfaces, but have some “roughness” or some unevenness. Even if it is, these "roughness" and unevenness | corrugation can be absorbed and the molten metal heat retention apparatus 100 and the crucible fixing ring 200 can be made into close_contact | adherence state.

Next, the crucible fixing ring 200 and the auxiliary ring 300 will be described.
The crucible fixing ring 200 has a ring shape in appearance and has an outer diameter that is the same as that of the molten metal heat insulating device 100, but is lower than the height of the first furnace wall 120 in the vertical direction. And both ends are openings. The height in the vertical direction of the crucible fixing ring 200 (the height in the direction along the z axis) is “h1” as described above, which is from the first furnace wall 120 of the molten metal heat retaining device 100 to the crucible. This corresponds to the height at which 110 protrudes (see FIG. 2).
Such a crucible fixing ring 200 has a second furnace wall 210 made of a heat-resistant and heat-insulating member, and a crucible fixing ring metal frame 230 surrounding the second furnace wall 210.

The second furnace wall 210 includes a heat resistant wall 211 and a heat insulating wall 212 provided outside the heat resistant wall 211. The heat resistant wall 211 is made of a heat resistant member such as a heat resistant brick, and the heat insulating wall 212 is made of a heat insulating member such as ceramic.

At the lower end portion of the outer peripheral surface of the crucible fixing ring metal frame 230, a flange portion 231 (referred to as a lower end side flange portion 231) protruding in the horizontal direction is formed along the outer periphery of the crucible fixing ring metal frame 230, and At the upper end portion of the outer peripheral surface of the fixing ring metal frame 230, a flange portion 232 (referred to as an upper end side flange portion 232) that protrudes in the horizontal direction is formed along the outer periphery of the crucible fixing ring metal frame 230.

The lower end side flange portion 231 and the upper end side flange portion 232 are respectively provided with guide pin insertion holes (not shown) for inserting the guide pins GP, for example, at four locations at equal intervals. Further, on the outer peripheral surface of the crucible fixing ring metal frame 230, hooks 233 (see FIG. 1) used when the crucible fixing ring 200 is lifted by a crane or the like are provided at, for example, four locations at equal intervals.

By the way, in the crucible fixing ring 200, the heat-resistant wall 211, the heat insulating wall 212, and the crucible fixing ring metal frame 230 protrude from the inner peripheral surface of the crucible fixing ring metal frame 230 toward the center direction (radial direction). They are connected by an iron rod (not shown).

That is, the heat-resistant wall 211 and the heat insulating wall 212 of the crucible fixing ring 200 are respectively formed on the inner peripheral surface side of the crucible fixing ring metal frame 230 by molding. Specifically, a plurality of (for example, six) iron rods (referred to as anchor bolts) projecting in the center direction of the crucible fixing ring metal frame 230 are arranged on the inner peripheral surface of the crucible fixing ring metal frame 230. It fixes by welding for every predetermined space | interval (for example, 60 degree angle) along a direction.

And the heat-resistant wall 211 and the heat-insulating wall 212 are respectively formed on the inner peripheral surface side of the crucible fixing ring metal frame 230 by mold molding. Depending on the size and weight of the crucible fixing ring 200, the anchor bolts may be provided in a plurality of stages (for example, two stages) in the vertical direction (the height direction of the crucible fixing ring 200).

Since the crucible fixing ring 200 has such a structure, the heat-resistant wall 211 and the heat insulating wall 212 and the crucible fixing ring metal frame 230 are surely connected. For this reason, when a wire is hooked on the hook 233 of the crucible fixing ring metal frame 230 and lifted by a crane or the like, the entire crucible fixing ring 200 can be lifted.

In addition, a gap for filling the crucible fixing seal 250 (referred to as a seal embedding gap 260) is formed between the inner wall surface of the crucible fixing ring 200, that is, the inner wall surface of the heat-resistant wall 211, with the opening-side outer wall of the crucible 110. Yes. The material of the crucible fixing seal 250 is not particularly limited as long as it is a material excellent in heat resistance, airtightness, and cushioning properties, but a ceramic rope or the like can be preferably used.

FIG. 3 is an enlarged view showing a part of the crucible fixing ring 200 and the upper end portion of the crucible 110. As shown in FIG. 3, the inner wall surface 211 a of the second furnace wall 210 in the crucible fixing ring 200 in the seal embedding gap 260, that is, the inner wall surface 211 a of the heat-resistant wall 211, the seal embedding gap 260 is the upper surface of the second furnace wall 210. The inclined surface becomes narrower as it goes from the bottom to the bottom. Hereinafter, the inner wall surface 211a may be referred to as an “inclined surface 211a”. The inclination angle (referred to as θ1) of the inclined surface 211a with respect to the z axis (vertical axis) is larger than the inclination angle (referred to as θ2) relative to the z axis (vertical axis) of the opening-side outer wall surface of the crucible 110. Yes.

In the metal melting furnace 10 according to the embodiment, the inclination angle θ1 of the inclined surface 211a is an inclination angle obtained by adding 5 degrees to the inclination angle θ2 of the opening-side outer wall surface of the crucible 110 (θ1 = θ2 + 5 degrees). The angle added to the angle θ2 is not limited to 5 degrees, and an optimal value can be set as appropriate.

Note that, as shown in FIG. 3, the crucible fixing seal 250 embedded in the seal embedding gap 260 has a wedge-shaped cross section, so the crucible fixing seal 250 may be referred to as a “wedge-shaped seal 250”.

Since the crucible fixing ring 200 has such a structure, when the crucible fixing ring 200 is placed on the molten metal heat insulating device 100, the opening-side outer wall surface of the crucible 110 is placed on the outer periphery of the opening-side outer wall surface. Therefore, the crucible 110 can be securely fixed.

The explanation returns to FIG. The crucible fixing ring 200 is provided with a temperature sensor TS2 (referred to as a crucible upper temperature sensor TS2) capable of measuring the temperature of the opening-side outer wall surface of the crucible 110. The crucible upper part temperature sensor TS <b> 2 is disposed along the upper surface of the crucible fixing ring 200 from the outside of the crucible fixing ring 200, and the tip is bent at an angle along the opening-side outer wall surface of the crucible 110.

In the crucible upper temperature sensor TS2, a portion bent at an angle along the opening-side outer wall surface of the crucible 110 is referred to as a “tip bent portion P2”. Further, the front end bent portion P2 of the crucible upper temperature sensor TS2 is sandwiched between the opening-side outer wall surface of the crucible 110 and the wedge-shaped seal 250, so the front-end bent portion P2 is the opening-side outer wall surface of the crucible 110. The temperature of the outer wall surface on the opening side of the crucible 110 can be measured with high accuracy.

The auxiliary ring 300 is placed on the crucible fixing ring 200 configured as described above. At this time, an auxiliary ring seal 270 is laid between the crucible fixing ring 200 and the auxiliary ring 300.

The auxiliary ring 300 has a ring shape in appearance and has an outer diameter that is the same as that of the molten metal heat retaining device 100, but is lower than the height of the first furnace wall 120 in the vertical direction. And both ends are openings.
Such a crucible fixing ring 200 has a third furnace wall 310 made of a heat-resistant and heat-insulating member, and an auxiliary ring metal frame 330 surrounding the third furnace wall 310.

The third furnace wall 310 includes a heat resistant wall 311 and a heat insulating wall 312 provided outside the heat resistant wall 311. The heat resistant wall 311 is made of a heat resistant member such as a heat resistant brick, and the heat insulating wall 312 is made of a heat insulating member such as ceramic.

Further, the inner diameter of the auxiliary ring 300 (the diameter D1 of the space surrounded by the heat-resistant wall 311) is the same as the outer diameter of the opening-side end 110a of the crucible 110 or is larger than the outer diameter of the opening-side end 110a of the crucible 110. It is set slightly larger. Thus, when the auxiliary ring 300 is placed on the crucible fixing ring 200, the weight of the auxiliary ring 300 is not directly applied to the crucible 110. Furthermore, even when a combustion device 400 described later is placed on the auxiliary ring 300, the weight of the auxiliary ring 300 and the combustion device 400 is not directly applied to the crucible 110.

As described above, the crucible 110 is a so-called baked product obtained by compression-firing graphite and is easily damaged. For this reason, a structure in which a large weight is directly applied to the crucible 110 also damages the crucible 110. However, as described above, the weight of the structure installed above the crucible 110 is the weight of the crucible 110. Therefore, the crucible 110 can be prevented from being damaged and the life of the crucible 110 can be extended.

Further, at the lower end portion of the outer peripheral surface of the auxiliary ring metal frame 330, a flange portion 331 (referred to as a lower end side flange portion 331) that protrudes in the horizontal direction is formed along the outer periphery of the auxiliary ring metal frame 330. At the upper end portion of the outer peripheral surface of the ring metal frame 330, a flange portion 332 (referred to as an upper end side flange portion 332) that protrudes in the horizontal direction is formed along the outer periphery of the auxiliary ring metal frame 330. In addition, guide pin insertion holes (not shown) for inserting the guide pins GP are respectively provided in the lower end side flange portion 331 and the upper end side flange portion 332, for example, at four locations at equal intervals. Further, on the outer peripheral surface of the auxiliary ring metal frame 330, hooks 333 (see FIG. 1) used when the auxiliary ring 300 is lifted by a crane or the like are provided at, for example, four locations at equal intervals.

The heat-resistant wall 311 and the heat insulating wall 312 of the auxiliary ring 300 and the auxiliary ring metal frame 330 are connected by the same structure as that of the crucible fixing ring 200. For this reason, also in the auxiliary ring 300, as in the crucible fixing ring 200, when the wire is hooked on the hook 333 of the auxiliary ring metal frame 330 and lifted by a crane or the like, the entire auxiliary ring 300 can be lifted.

Further, the auxiliary ring 300 is provided with a temperature sensor insertion hole 340 into which a molten metal temperature sensor TS3 (see FIG. 6B) for measuring the temperature in the crucible 110 during the melting operation can be inserted. . The temperature sensor insertion hole 340 can be attached and detached with a plug 340a (see FIG. 6A) for closing the temperature sensor insertion hole 340. When the temperature measurement is not performed, the plug 340a is used. The temperature sensor insertion hole 340 is closed.

Further, the auxiliary ring seal 270 is laid between the auxiliary ring 300 and the crucible fixing ring 200 as described above. Specifically, the auxiliary ring seal 270 is laid between the third furnace wall 310 in the auxiliary ring 300 and the second furnace wall 210 in the crucible fixing ring 200. At this time, the auxiliary ring seal 270 is positioned by an auxiliary ring seal receiving plate 360 made of metal (for example, iron).

FIG. 4 is a view showing the auxiliary ring seal receiving plate 360 taken out. As shown in FIG. 4, the auxiliary ring seal receiving plate 360 is a disk having the same diameter as the outer diameter including the

flange portions

231 and 232 of the crucible fixing ring metal frame 230 or the

flange portions

331 and 332 of the auxiliary ring metal frame 330. An opening 361 having a shape that is sufficiently larger than the outer diameter of the opening-side end 110a of the crucible 110 (the inner diameter D1 of the auxiliary ring 300) is formed at the center. The inner diameter of the auxiliary ring seal 270 is the same as the inner diameter D1 of the auxiliary ring 300.

Further, an auxiliary ring seal guide wall 362 for guiding the laying of the auxiliary ring seal 270 is formed at the edge of the opening 361 along the edge of the opening. The height h2 of the auxiliary ring seal guide wall 362 is lower than the thickness dimension t1 of the auxiliary ring seal. The auxiliary ring seal 270 is laid on the upper surface of the second furnace wall 210 in the crucible fixing ring 200 so that the outer periphery of the auxiliary ring seal 270 is along the inner periphery of the auxiliary ring seal guide wall 362.

Further, four guide pin through holes 363 are formed in the auxiliary ring seal receiving plate 360. These guide pin through holes 363 are the same as guide pin insertion holes (not shown) formed in the

flange portions

231 and 232 of the crucible fixing ring metal frame 230 or the

flange portions

331 and 332 of the auxiliary ring metal frame 330. Formed in position. The auxiliary ring seal receiving plate 360 is installed between the crucible fixing ring 200 and the auxiliary ring 300.

Next, the combustion apparatus 400 will be described. Combustion device 400 is mounted on auxiliary ring 300, has a predetermined space at the center, and has a fourth furnace wall 410 made of a heat-resistant and heat-insulating member, and a combustion device that surrounds fourth furnace wall 410. A metal frame 430 and a burner 440 provided in the space of the fourth furnace wall 410 are provided. In addition, the hook 431 used when lifting up the combustion apparatus 400 with a crane etc. is provided in the outer peripheral surface of the combustion apparatus metal frame 430, for example in four places at equal intervals.

The fourth furnace wall 410 includes a heat resistant wall 411 and a heat insulating wall 412 provided outside the heat resistant wall 411. In addition, since the combustion apparatus 400 becomes higher temperature than the crucible fixing ring 200 and the auxiliary | assistant ring 300, it is preferable that the heat insulation wall 412 uses a member excellent in not only heat insulation but heat resistance.

The burner 440 dissolves the metal to be melted put in the crucible 110 by an open flame, takes in, for example, LPG (liquefied propane gas) from the fuel supply pipe 441 as fossil fuel, and air necessary for combustion into air. It takes in from the intake port 442 and fires a flame from the nozzle 443. Note that the burner 440 used in the metal melting furnace 10 according to the embodiment is a heat exchange type burner that preheats air taken in from the air intake port 442 with exhaust gas. For this reason, since the air which entered from the air intake port 442 is warmed by the exhaust gas, the combustion efficiency is good and the air intake port 442 and the exhaust port 444 can be made small.

Further, the burner 440 is provided with a combustion control device (not shown) for controlling the combustion state. This combustion control device adjusts the amount of air and the amount of combustion so as to achieve an optimal combustion state. A combustion chamber 450 is formed by the space surrounded by the combustion device 400 and the heat-resistant wall 311 of the auxiliary ring 300.

In addition, the heat-resistant wall 411 and the heat insulating wall 412 in the combustion apparatus 400 and the combustion apparatus metal frame 430 are connected by a structure substantially similar to the crucible fixing ring 200 and the auxiliary ring 300. For this reason, in the combustion apparatus 400 as well as the crucible fixing ring 200 and the auxiliary ring 300, when the wire is hooked on the hook 431 of the combustion apparatus metal frame 430 and lifted by a crane or the like, the entire combustion apparatus 400 can be lifted. .

Further, a combustion device seal 380 is laid between the combustion device 400 and the auxiliary ring 300. Specifically, the combustion device seal 380 is laid between the fourth furnace wall 410 in the combustion device 400 and the third furnace wall 310 in the auxiliary ring 300. At this time, the combustion device seal 380 is positioned by the combustion device seal receiving plate 460.

The combustion device seal seal receiving plate 460 has substantially the same configuration as the auxiliary ring seal receiving plate 360 shown in FIG. The combustion device seal receiving plate 460 is different from the auxiliary ring seal receiving plate 360 in that the combustion device positioning protrusion 469 (for positioning the combustion device 400 when the combustion device 400 is placed on the auxiliary ring 300). (See FIG. 2).

The combustion apparatus positioning protrusion 469 is a ring-shaped protrusion that extends along the outer periphery of the lower end of the combustion apparatus metal frame 430 of the combustion apparatus 400. For this reason, when the combustion device 400 is placed on the auxiliary ring 300, the combustion device 400 is placed on the auxiliary ring 300 along the combustion device positioning protrusion 469 so that the combustion device 400 is placed on the auxiliary ring 300. 300 can be placed at an appropriate position.

Next, the rotary degassing apparatus 500 (see FIG. 1) will be described. The rotary degassing device 500 removes impurities such as hydrogen gas contained in the molten metal in the crucible 110 when the metal to be melted is melted to be in a molten metal state. It has a configuration having a disk-shaped rotating body 520 provided at the tip of the shaft 510.

The rotary degassing apparatus 500 configured as described above is installed so as to be able to move on the xy plane and in the vertical direction (direction along the z axis), for example. It can be immersed in the molten metal in the crucible 110. For example, the rotary body 520 can be immersed in the molten metal of the crucible 110 by lowering the rotary degassing device 500 after the combustion process 400 is finished and the auxiliary ring 300 is removed. Then, the rotating body 520 is rotated in a state where the rotating body 520 is immersed in the molten metal, and an inert gas such as argon gas and nitrogen gas microbubbled from the rotating body 520 can be generated in the molten metal. It is like that.

As described above, the metal melting furnace 10 according to the embodiment includes the melting furnace main body 10A (the molten metal heat retaining device 100, the crucible fixing ring 200, the auxiliary ring 300, and the combustion device 400) and the rotary degassing device 500. The melting furnace main body 10A has a four-layer structure in which four structures of a molten metal heat retaining device 100, a crucible fixing ring 200, an auxiliary ring 300, and a combustion device 400 are stacked. Each of these structures has a separable structure.

Since the melting furnace main body 10A in the metal melting furnace 10 according to the embodiment has such a structure, it is necessary to repair or replace a certain structure among the structures constituting the melting furnace main body 10A. In such a case, only the structure to be repaired or replaced can be taken out and repaired or replaced. In this case, if the replacement of the individual structures is facilitated, it is not necessary to stop the operation for a long period of time, so that the production is not hindered.

That is, the metal melting furnace 10 according to the embodiment has a structure in which the melting furnace main body 10A is further subdivided as compared with the metal melting furnace 900 disclosed in Patent Document 1, so these structures are temporarily assumed. Repair or replacement work can be facilitated when it is necessary to repair or replace a certain structure of the body.

In particular, in this type of metal melting furnace, the periphery of the combustion device 400 is exposed to high temperatures, and is easily damaged by heat. In the metal melting furnace 10 according to the embodiment, the portion that is easily exposed to a high temperature has two structures of the combustion device 400 and the auxiliary ring 300, and these can be divided individually. For this reason, when damage due to heat progresses and repair or replacement becomes necessary, only the structure that needs repair or replacement can be taken out and repaired or replaced. For example, when the auxiliary ring 300 is damaged, only the auxiliary ring 300 needs to be repaired or replaced, so that maintainability can be improved.

Next, when assembling the melting furnace main body 10A described in FIG. 1 and FIG. 2 for explaining the assembling procedure of the melting furnace main body 10A in the metal melting furnace 10 according to the embodiment, first, the molten metal in which the crucible 110 is accommodated. A ring-shaped molten metal heat insulation device seal 190 is laid on the upper surfaces of the heat resistant wall 121 and the heat insulation wall 122 (the upper surface of the first furnace wall 120) in the heat retention device 100. The molten metal heat insulating device seal 190 is laid so that the outer peripheral surface thereof is along the inner surface of the metal case 130. Thereby, since the molten metal heat insulation apparatus seal | sticker 190 is positioned by the internal peripheral surface of the metal case 130, the horizontal shift | offset | difference can be prevented.

Thus, the crucible fixing ring 200 is placed in a state where the molten metal heat insulation device seal 190 is laid. At this time, each guide pin insertion hole (not shown) formed in the flange 131 of the metal case 130 and each guide pin insertion hole (not shown) formed in the lower end side flange 231 of the crucible fixing ring metal frame 230. The crucible fixing ring 200 is placed so as to match each other (not shown). Then, the guide pin GP is inserted into each guide pin insertion hole. Thereby, the crucible fixing ring 200 can be attached to the molten metal heat retaining device 100.

In this way, by attaching the crucible fixing ring 200 to the molten metal heat insulating device 100, the molten metal heat insulating material laid between the first furnace wall 120 in the molten metal heat insulating device 100 and the second furnace wall 210 in the crucible fixing ring 200. The device seal 190 is pressed by the weight of the crucible fixing ring 200, and the molten metal heat retaining device 100 and the crucible fixing ring 200 are in close contact with each other.

Then, a wedge seal 250 is embedded in the “sealing gap 260” formed between the outer wall surface on the opening side of the crucible 110 and the inner wall surface 211a (inclined surface 211a) of the heat-resistant wall 211 in the crucible fixing ring 200. To do. At this time, the upper end of the wedge-shaped seal 250 is made to protrude slightly upward from the upper surface of the crucible fixing ring 200. Accordingly, the crucible 110 is securely fixed by the crucible fixing ring 200. In other words, the wedge-shaped seal 250 is added with the weight of the auxiliary ring 300 and the combustion device 400, whereby the wedge-shaped seal 250 tries to move downward along the z-axis. The force which presses the outer wall of the crucible 110 works. Thereby, the crucible 110 can be fixed reliably.

Subsequently, the auxiliary ring 300 is placed on the crucible fixing ring 200. At this time, first, the auxiliary ring seal receiving plate 360 is placed on the upper surface of the second furnace wall 210 of the crucible fixing ring 200, and the auxiliary ring seal 270 is laid on the auxiliary ring seal receiving plate 360, and the auxiliary ring seal 270 is provided thereon. The ring 300 is placed. At this time, a guide pin insertion hole (not shown) formed in the upper end side flange 232 of the crucible fixing ring metal frame 230, a guide pin insertion hole 363 formed in the auxiliary ring seal receiving plate 360, The seal receiving plate and the 360 auxiliary ring 300 are attached to the crucible fixing ring 200 so that the guide pin insertion holes (not shown) formed in the lower end side flange portion 331 of the auxiliary ring metal frame 330 are aligned with each other. Place. Then, the guide pin GP is inserted into each guide pin insertion hole. Thereby, the auxiliary ring 300 can be attached to the crucible fixing ring 200.

The auxiliary ring seal 270 is disposed so that the outer peripheral surface thereof is along the inner peripheral surface of the auxiliary ring seal guide wall 362 formed on the seal receiving plate 360. As a result, the auxiliary ring seal 270 is positioned by the auxiliary ring seal guide wall 362, so that a horizontal shift can be prevented.

By attaching the auxiliary ring 300 to the crucible fixing ring 200 in this way, the auxiliary ring seal 270 laid between the auxiliary ring 300 and the crucible fixing ring 200 is pressed by the weight of the auxiliary ring 300. The auxiliary ring 300 and the crucible fixing ring 200 are in close contact with each other.

Subsequently, the combustion device 400 is placed on the auxiliary ring 300. At this time, first, the combustion apparatus seal receiving plate 460 is placed on the upper surface of the third furnace wall 310 in the auxiliary ring 300. In this case, a guide pin insertion hole (not shown) formed in the upper end side flange 332 of the auxiliary ring metal frame 330 and a guide pin insertion hole (not shown) formed in the combustion device seal receiving plate 460. .)) Is placed on the auxiliary ring 300 so that they match each other.

And then insert the guide pin into each guide pin insertion hole. As described above, after the combustion device seal receiving plate 460 is attached to the upper surface of the auxiliary ring 300, the combustion device seal 380 is laid on the combustion device seal receiving plate 460. The combustion device seal 380 is installed on the combustion device seal receiving plate 460 in the same manner as the auxiliary ring seal 270.

In such a state, the combustion device 400 is placed on the combustion device seal receiving plate 460. At this time, the combustion device 400 is placed on the seal receiving plate 460 using the combustion device positioning protrusion 469 provided on the combustion device seal receiving plate 460 as a guide. By placing the combustion device 400 on the auxiliary ring 300 in this way, the combustion device seal 380 laid between the combustion device 400 and the auxiliary ring 300 is pressed by the weight of the combustion device 400. The combustion device 400 and the auxiliary ring 300 are in close contact with each other.

The melting furnace body 10A can be assembled by the procedure as described above (see FIGS. 1 and 2). The melting furnace main body 10A assembled in this way is not easily displaced because most of the individual structures have a weight of 100 kg or more.

Moreover, since it has such a weight, a large pressing force is applied to each seal (the molten metal heat insulation device seal 190, the auxiliary ring seal 270, and the combustion device seal 380), and the structures are brought into close contact with each other. For this reason, while being able to make the sealing degree with respect to the melting furnace main body 10A exterior of the melting furnace main body 10A of the combustion chamber 450 high, the sealing degree with respect to the melting furnace main body 10A exterior of the thermal storage room 150 can be made high. Thereby, it is possible to prevent the combustion heat of the burner 440 and the heat from the electric heater from escaping to the outside, so that it is possible to increase the thermal efficiency when melting the metal to be melted and the heat retention power when warming the molten metal.

Also, the degree of sealing between the combustion chamber 450 and the thermal storage room 150 can be increased. Thereby, the effect which prevents the combustion heat and combustion gas of the burner 440 from flowing into the thermal storage room 150 can be enhanced. In addition, since the combustion heat of the burner 440 reaches 1300 degreeC or more, the bad influence given to the electric heater 180 grade | etc., Can be suppressed by preventing such a high heat | fever flowing into a heat retention chamber.

In addition, since a wedge-shaped seal 250 is embedded between the crucible fixing ring 200 and the crucible 110, the effect of preventing the combustion heat and combustion gas of the burner 440 from flowing into the thermal storage room 150 is further enhanced. be able to. Note that the wedge-shaped seal 250 is added with the weight of the auxiliary ring 300 and the combustion device 400, whereby the wedge-shaped seal 250 tries to move downward along the z-axis. Force to press the outer wall surface on the opening side of the crucible 110). As a result, the hermeticity of the thermal storage room 150 becomes higher, and the effect of preventing the combustion heat and combustion gas of the burner 440 from flowing into the thermal storage room 150 can be further enhanced.

Next, a molten metal generation method when generating a molten metal using the metal melting furnace 10 according to the embodiment will be described.

FIG. 5, FIG. 6 and FIG. 7 are diagrams for explaining each step of the molten metal production method when producing molten metal using the metal melting furnace 10 according to the embodiment. FIGS. 5 (a) to 5 (c) are diagrams for explaining the melting preparation step in the molten metal production step. Moreover, FIG. 6A and FIG. 6B are diagrams for explaining the melting step and the molten metal heat retaining step in the molten metal generation step. FIGS. 7A and 7B are views for explaining the impurity removal step in the molten metal generation step. In FIGS. 5 to 7, some of the reference numerals are omitted to simplify the drawings.

1. Dissolving preparation step First, as shown in FIG. 5 (a), and remove the combustion device 400, the state of the crucible fixing ring 200 to melt insulation device 100 and the auxiliary ring 300 is placed. At this time, the combustion device seal receiving plate 460 and the combustion device seal 380 are laid on the upper surface of the auxiliary ring 300. The combustion device seal 380 is preferably covered with a seal protective cover (not shown).

In such a state, as shown in FIG. 5B, the metal 600 to be melted is put into the crucible 110. The amount of the metal 600 to be melted introduced into the crucible 110 is determined in consideration of the capacity of the crucible 110. As the metal 600 to be melted, a cast remaining material separated from an aluminum ingot and a cast product generated by the previous casting operation (a cast part corresponding to a pouring gate, a cast part corresponding to a runner, a cast part corresponding to a feeder) Etc.).

It should be noted that when the metal 600 to be melted is put into the crucible 110, the metal 600 to be melted put into the crucible 110 may be put into the crucible so as not to protrude above the auxiliary ring 300.

That is, in the metal melting furnace 10 according to the embodiment, since the combustion device 400 is mounted on the auxiliary ring 300, the metal 600 to be melted introduced into the crucible 110 is located above the auxiliary ring 300. If it puts in a crucible so that it may not protrude, the combustion apparatus 400 can be mounted in the auxiliary | assistant ring 300. FIG.

In other words, in the metal melting furnace 10 according to the embodiment, due to the presence of the auxiliary ring 300, the protrusion of the metal 600 to be melted in the horizontal direction (the direction along the xy plane) is restricted from the beginning by the auxiliary ring 300. Therefore, the metal 600 to be melted can be put into the crucible 110 without worrying that the metal 600 to be melted “extends” in the horizontal direction (the direction along the xy plane). For this reason, workability at the time of charging the metal 600 to be melted into the crucible 110 can be improved, and the amount of the metal 600 to be melted with respect to the capacity of the crucible 110 can be set to the maximum. Can fully utilize the capacity. Thereby, the productivity of the molten metal can be improved.
Then, from the state of FIG. 5B, the seal protection cover (not shown) of the combustion device seal 380 is removed, and the combustion device 400 is placed on the auxiliary ring 300 (see FIG. 5C).

2. Following dissolution step and molten metal incubating process, as shown in FIG. 6 (a), it starts to dissolve against the burner 440 of the combustion device 400 flame 445 to the molten metal 600. At this time, the temperature sensor insertion hole 340 into which the molten metal temperature sensor TS3 can be inserted is closed with the plug 340a. This is to prevent combustion heat from escaping to the outside when the metal 600 to be melted is melted by the burner 440 of the combustion apparatus 400.

In addition, in order to prevent oxidation of aluminum which is the metal 600 to be dissolved, combustion is performed with a reducing flame, and the inside of the combustion chamber 450 is in an oxygen deficient state. At this time, when air enters the combustion chamber 450, the aluminum is oxidized and consumed. However, in the metal melting furnace 10 according to the embodiment, the seals of each part (the molten metal heat insulation device seal 190, the wedge seal 250, the auxiliary ring). Since the seal 270, the combustion device seal 380) and the like have high sealing properties and the sealing property of the combustion chamber 450 is maintained, it is possible to suppress aluminum from being oxidized and consumed, and to improve fuel consumption. In particular, since the auxiliary ring seal 270 and the combustion device seal 380 are positioned by the

seal receiving plates

360 and 460, respectively, since they have high positional accuracy, high sealing performance can be maintained for a long time.

When melting is performed by the flame of the burner 440 in this way, the electric heater 180 is energized at a predetermined timing, and a melting / heating process in which combustion by the burner 440 and heating by the electric heater 180 are combined, that is, “burner heater” Perform combined melting and heating process. Note that the energization start timing for starting energization of the electric heater 180 affects fuel consumption and dissolution efficiency. According to the experiments conducted by the inventors of the present invention, the metal 600 to be melted begins to melt, and the temperature of the bottom outer wall surface of the crucible 110 becomes 550 ° C. (the temperature measured by the crucible bottom temperature sensor TS1 is 550 ° C.). It has been found that it is preferable to set the time when the electric heater 180 is energized.

Then, for a while from the start of energization of the electric heater 180, a “melting / heating process using the burner / heater” in which the burner 440 and the electric heater 180 are used together is performed, and the temperature measured by the crucible bottom temperature sensor TS 1 When the temperature near 630 ° C. is indicated, the operation of the burner 440 is temporarily stopped, the molten metal temperature sensor TS3 is inserted into the temperature sensor insertion hole 340 (see FIG. 6B), and the temperature in the crucible 110 is monitored, The melting state in the crucible 110 is monitored.

At this time, about 60% of the upper part is in a liquid state in the crucible 110, and the lower part in the crucible 110 is in a state where the solid and the liquid are mixed. Here, the operation of the burner 440 is stopped, the temperature is raised by heating with the electric heater 180, and the metal 600 to be melted is melted into a molten metal state. Thereafter, the process proceeds to a “molten heat retaining process” in which the molten metal in the crucible 110 is kept warm by the electric heater 180 so that the temperature is suitable for the casting operation.

When about 60% of the upper part in the crucible 110 is in a liquid state and the lower part in the crucible 110 is in a state where the solid and the liquid are mixed, the operation of the burner 440 is stopped and the electric heater 180 is heated. The reason for doing this is as follows.

That is, when the metal 600 to be melted is solid, the melting efficiency by the flame from the burner 440 is high, but when the upper surface in the crucible 110 becomes liquefied, the liquefied metal (in this case, aluminum) is the surface. Therefore, it becomes difficult for the heat of combustion from the flame from the burner 440 to be transmitted to the inner part of the crucible 110 (the part where the melted metal 600 that is not liquefied remains exists). This is because much time and energy are required until the entire metal 600 to be melted in 110 is melted into a molten metal.

Therefore, when about 60% of the upper part in the crucible 110 is in a liquid state and the lower part in the crucible 110 is in a state where the solid and the liquid are mixed, the operation of the burner 440 is stopped and heating is performed only by the electric heater 180. By raising the temperature, the metal 600 to be melted can be efficiently melted to form the molten metal 700, and thereafter, the molten metal 700 can be maintained at a temperature suitable for the casting operation. In addition, since the temperature control by the electric heater 180 can be performed with high accuracy, the temperature of the molten metal 700 can be appropriately maintained at a temperature suitable for the casting operation.

Control of the electric heater 180 can be performed by an electric heater control unit (not shown). That is, the electric heater control unit controls the electric heater 180 based on the temperature of the molten metal 700 in the crucible 110 so that the temperature of the molten metal 700 is maintained at a predetermined temperature. Thereby, the molten metal 700 in the crucible 110 can always be maintained at a temperature suitable for the casting operation.

3. Impurity removing step When the molten metal 700 in the crucible 110 reaches a temperature suitable for the casting operation, the combustion device 400 is removed and the auxiliary ring 300 is removed (see FIG. 7A). The combustion device 400 and the auxiliary ring 300 are removed by a crane (not shown). In addition, when removing the auxiliary | assistant ring 300, it carries out in the state which pulled out the guide pin GP.

Then, when the combustion device 400 and the auxiliary ring 300 are removed as shown in FIG. 7A, the rotating body 520 of the rotary degassing device 500 as the impurity removing device is immersed in the molten metal 700, Impurity removal work is performed. At this time, the auxiliary ring seal 270 on the crucible fixing ring 200 is preferably covered with a seal protection cover (not shown).

As shown in FIG. 7B, the impurity removal operation is performed by immersing the rotating body 520 of the rotary degassing apparatus 500 in the molten metal 700 in the crucible 110 and rotating the rotating body 520 into argon gas that is microbubbled. By generating it, impurities such as hydrogen gas contained in the molten metal 700 are levitated and removed. By removing impurities in this way, the molten metal 700 in the crucible 110 becomes of high quality. When performing the impurity removal operation in such an impurity removal step, the impurity removal operation can be repeated until the required quality standard is reached.

In this way, when a high-quality molten metal that meets the required quality standards is generated, the rotary degassing device 500 is removed and a temperature sensor TS4 for controlling the molten metal temperature is installed as shown in FIG. It puts in the molten metal 700, measures a molten metal temperature, and controls the electric heater 180 so that the molten metal 700 is maintained at a temperature suitable for casting based on the measurement result. The temperature sensor TS4 for controlling the molten metal temperature may be the same as the molten metal temperature sensor TS3 used in FIG.

In the state of FIG. 7C, the auxiliary ring 300 does not exist, and the opening of the crucible 110 is flush with the upper surface of the crucible fixing ring 200. The distance to the liquid surface is short from the upper surface of the crucible fixing ring 200. For this reason, the work of drawing out the molten metal 700 becomes easy, and the casting work can be performed efficiently.

FIG. 8 is a diagram for explaining the melting efficiency when the melting work of the metal 600 (to be aluminum) is actually performed using the metal melting furnace 10 according to the embodiment. FIG. 8A is a diagram showing various conditions when the melting operation is performed, and FIG. 8B is a diagram illustrating a metal melting furnace 10 (see FIG. 8A) based on the conditions shown in FIG. It is a figure which compares and compares the melting efficiency by a metal melting furnace of a hybrid type), and the melting efficiency by the metal melting furnace only of LPG gas. FIG. 8 shows the melting efficiency when the metal melting furnace 10 according to the embodiment is used only for melting, and heat retention and the like use other crucibles.

In FIG. 8B, the white square represents the melting efficiency of the metal melting furnace 10 according to the embodiment, and the thick solid line represents the melting efficiency of the LPG (Liquefied Petroleum Gas) only. Show. In FIG. 8 (b), the horizontal axis indicates the day when the melting operation was performed (melting date), and the vertical axis indicates the melting efficiency (%) on each melting date (1 to 5 days). .

In this case, the melting efficiency in FIG. 8 (b) is assumed to be the ratio (%) of heat used to the theoretical melting heat of aluminum. Here, α is the theoretical melting heat of aluminum, α is the actual amount of gas used expressed as a value β converted to heat per 1 kg of aluminum, and the actual amount of electricity used is expressed as a value γ converted into heat per 1 kg of aluminum. Then, the melting efficiency (referred to as A1) by the metal melting furnace 10 according to the embodiment is as follows.
A1 (%) = α / (β + γ) × 100
The melting efficiency (referred to as A2) in a metal melting furnace using only LPG gas is
A2 (%) = α / β × 100
It is represented by

The theoretical heat of fusion α of aluminum is 1 kg when the weight of aluminum is
α = aluminum weight × specific heat × (melting work temperature−atmosphere temperature) + aluminum weight × melting latent heat = 271.6 Kcal / Kg
Is required.

As shown in FIG. 8 (b), the melting efficiency of the LPG gas-only metal melting furnace is about 10% at most on the day of each melting operation. On the other hand, the melting efficiency of the metal melting furnace (hybrid metal melting furnace) according to the embodiment is 25 to 30%, and it was found that a higher melting efficiency was obtained compared to a metal melting furnace only with LPG gas.

FIG. 9 is a diagram illustrating another example of a molten metal generation method in the metal melting furnace 10 according to the embodiment. In the molten metal production method shown in FIG. 9, two molten metal heat retaining devices 100A with a crucible fixing ring (referred to as a molten metal heat retaining device with a crucible fixing ring) in a state where the crucible fixing ring 200 is installed in the molten metal heat retaining device 100 are used. And the molten metal heat retaining device 100B with the second crucible fixing ring), and one auxiliary ring 300 and one combustion device 400 are prepared, respectively. The molten metal heat generating device 100B with two crucible fixing rings, one auxiliary ring 300, and one combustion device 400 are used to efficiently generate molten metal.

In FIG. 9, in the molten metal heat retaining device 100A with the first crucible fixing ring, it is assumed that a high-quality molten metal 700 from which impurities are removed is generated by the procedure described in FIGS. In addition, in the molten metal heat retaining device 100A with the first crucible fixing ring after the generation of the molten metal 700 is completed, the molten metal 700 in the crucible 110 is maintained at a temperature suitable for casting work by the electric heater 180. It is in a state where work can be performed.

As described above, when the generation of the molten metal is finished in one molten metal heat retaining device (the molten metal heat retaining device 100A with the first crucible fixing ring), the auxiliary ring 300 and the combustion removed from the molten metal heat retaining device 100A with the first crucible fixing ring. The apparatus 400 is attached to the molten metal heat retaining apparatus 100B with the second crucible fixing ring. And the to-be-melted metal 600 is put into the molten metal heat retention apparatus 100B with the said 2nd crucible fixing ring, and a molten metal is produced | generated in the molten metal heat retention apparatus 100B with the said 2nd crucible fixation ring. In this case, the molten metal generation procedure can be performed in the order of the steps shown in FIGS.

In addition, while the molten metal is generated in the molten metal heat retaining device 100B with the second crucible fixing ring, the molten metal is pumped out in the molten metal heat insulating device 100A with the first crucible fixing ring. It is to be noted that the pumping operation of the molten metal generally does not pump out all the molten metal contained in the crucible 110 but leaves about 1/3 of the total amount of the molten metal contained in the crucible 110.

When the generation of the molten metal is completed in the molten metal heat retaining device 100B with the second crucible fixing ring, the combustion device 400 and the auxiliary ring 300 are removed from the molten metal heat retaining device 100B with the second crucible fixing ring, and the removed combustion is performed. The apparatus 400 and the auxiliary ring 300 are attached to the molten metal heat retaining apparatus 100A with the first crucible fixing ring. And the to-be-melted metal 600 is put into the molten metal heat retention apparatus 100A with the said 1st crucible fixing ring, and a molten metal is produced | generated in the molten metal heat retention apparatus 100A with the said 1st crucible fixation ring. While the molten metal is generated in the molten metal heat retaining device 100A with the first crucible fixing ring, the molten metal pumping operation is performed in the molten metal heat insulating device 100B with the second crucible fixing ring. Such an operation is sequentially repeated until a necessary amount of molten metal is generated.

As shown in FIG. 9, by alternately performing a molten metal generating operation and a molten metal pumping operation, a crucible type melting furnace such as the metal melting furnace 10 according to the embodiment is continuous as in the continuous melting furnace. Therefore, it is possible to perform an operation of generating a molten metal and an operation of pumping out the molten metal, and high productivity comparable to that of a continuous melting furnace can be obtained.

In FIG. 9, melting and pumping are alternately performed using two molten metal heat retaining devices with crucible fixing rings, but it is possible to use three or more molten metal heat retaining devices with crucible fixing rings. By using three or more molten metal heat retaining devices with crucible fixing rings, the molten metal generating operation and the molten metal pumping operation can be performed more efficiently.

Note that the present invention is not limited to the above-described embodiment, and modifications such as those shown below can be made without departing from the gist of the present invention.

(1) In the above embodiment, the temperature sensor insertion hole 340 for measuring the temperature of the molten metal in the melting step is provided in the auxiliary ring 300, but the structure is not limited to this. You may make it provide.

FIG. 10 is a view shown for explaining a modification of the installation location of the temperature sensor insertion hole 340 for measuring the temperature of the molten metal. As shown in FIG. 10, the temperature sensor insertion hole 340 can also measure the temperature of the molten metal in the melting step by providing it in the combustion apparatus 400. Whether to provide the auxiliary ring 300 or the combustion device 400 can be determined in consideration of workability and the like. Further, the temperature sensor insertion hole 340 may be provided in both the auxiliary ring 300 and the combustion device 400, and may be selectively used as appropriate. In this case, the sensor insertion hole is preferably closed with a plug to prevent heat from flowing out whenever it is not used.

(2) In the above embodiment, the burner 440 is exemplified by a burner using LPG as fuel, but is not limited to LPG, and may be a burner using other fossil fuel. Further, the burner 440 is a heat exchange type burner, and by using such a heat exchange type burner, the combustion efficiency can be improved. However, the fuel supply amount and the air supply amount according to the melting state. By controlling this, it is possible to further improve the combustion efficiency, thereby further reducing fuel consumption.

In order to realize this, although not shown, an exhaust temperature sensor for measuring the exhaust temperature of the exhaust gas exhausted from the exhaust port 444 of the burner 440 is provided, and the exhaust temperature output from the exhaust gas temperature sensor is provided. Based on the information, a burner control mechanism for controlling the supply amount of fuel (LPG gas) supplied to the fuel supply pipe 441 and the intake amount of air taken in from the air intake port 442 is provided. Thus, by controlling the supply amount of fuel (LPG gas) and the intake amount of air based on the exhaust temperature, the combustion efficiency can be further improved. This is because the exhaust gas temperature and the combustion efficiency are correlated.

That is, at the initial stage of melting in the melting step, as shown in FIG. 5 (c), the metal 600 to be melted is almost full in the crucible 110 and the combustion chamber 450. The combustion gas with insufficient heat exchange with the metal 600 to be dissolved and the combustion air due to the increase in the pressure in the combustion chamber 450 is exhausted from the exhaust port 444 at a high temperature of about 1000 ° C. The

On the other hand, as the melting of the metal 600 to be melted progresses, the space of the combustion chamber 450 becomes wider, and the density of the combustion gas decreases, so that the temperature of the combustion gas decreases to about 600 ° C. and is exhausted from the exhaust port 444. .

From this point of view, in the initial stage of dissolution, the fuel supply amount and the air supply amount are controlled so as to reduce the fuel supply amount (LPG gas) supply amount and the air intake amount, thereby further improving the combustion efficiency. And by that. Fuel consumption can be further reduced. Such control can be realized by controlling the supply amount of fuel (LPG gas) and the intake amount of air based on the exhaust gas temperature information output from the exhaust gas temperature sensor.

(3) In the above embodiment, the electric heater 180 used in the molten metal heat insulating device 100 is exemplified by the case where the belt-shaped electric heater 180 that goes around the inner wall surface of the heat-resistant wall 121 is used. For example, an electric heater that covers the entire inner wall surface including the bottom surface of the heat-resistant wall 121 may be used.

(4) In the above-described embodiment, the structure of the molten metal heat retaining device 100, the crucible fixing ring 200, the auxiliary ring 300, and the combustion device 400 is doubled by a heat-resistant wall made of a heat-resistant member and a heat-insulated wall made of a heat-insulating member. Although it is a wall structure, it is not necessarily limited to such a structure, and has other structures as long as heat resistance and heat insulation can be secured, and safety and durability can be secured. It may be a thing.

DESCRIPTION OF SYMBOLS 10 ... Metal melting furnace, 10A ... Melting furnace main body, 100 ... Molten metal heat retention apparatus, 110 ... Crucible, 110a ... Opening side edge part, 120 ... 1st furnace wall, 121. ..Heat resistant wall, 122... Heat insulation wall, 130... Metal case, 131... Lower end side flange, 132 ... upper end side flange, 180 .. heater (electric heater), 190. -Molten heat insulation device seal, 200 ... crucible fixing ring, 210 ... second furnace wall, 211a ... inclined surface, 230 ... crucible fixing ring metal frame, 250 ... crucible fixing seal (wedge type) Seal), 260 ... gap (clearance gap), 270 ... auxiliary ring seal, 300 ... auxiliary ring, 310 ... third furnace wall, 330 ... auxiliary ring metal frame, 360 ..Auxiliary ring seal receiving plate, 362 Auxiliary ring seal guide wall, 380 ... combustion device seal, 400 ... combustion device, 410 ... fourth furnace wall, 430 ... combustion device metal frame, 440 ... burner, 500 ... Rotating degassing apparatus, 600 ... metal to be melted, 700 ... molten metal, TS1 ... crucible bottom temperature sensor, TS2 ... crucible top temperature sensor, TS3 ... molten metal temperature sensor

Claims

A metal melting furnace provided with a crucible that holds a molten metal in which the metal to be melted is charged and the melted metal is melted,
A first furnace wall having a bottomed container shape having a predetermined height in the vertical direction, and a heater provided on an inner wall surface of the first furnace wall to keep the molten metal warm, A molten metal heat retaining device for storing the crucible opening side outer wall surface so as to be exposed by a predetermined amount from the upper surface of the first furnace wall;
A ring-shaped second furnace wall that can be detachably mounted on the molten metal heat retaining device, and in a state of being mounted on the molten metal heat retaining device, the inner wall surface of the second furnace wall is the opening side of the crucible A crucible fixing ring for fixing the crucible by supporting it in a press-contact state along the outer periphery of the outer wall surface;
An auxiliary ring having a third furnace wall that can be detachably mounted on the crucible fixing ring, the inner diameter of the third furnace wall being the same as or slightly larger than the outer diameter of the opening side end of the crucible; ,
A fourth furnace wall that can be detachably mounted on the auxiliary ring and has a predetermined space in the center, and a metal to be melted that is provided in the space and placed in the crucible is melted by direct fire. A combustion device having a burner for
A metal melting furnace further comprising:
In the metal melting furnace according to claim 1,
A predetermined gap is formed between the inner wall surface of the second furnace wall in the crucible fixing ring and the outer wall surface on the opening side of the crucible, and a crucible fixing seal made of a heat-resistant member is formed in the gap in the opening of the crucible. A metal melting furnace which is embedded so as to go around the side outer wall surface.
In the metal melting furnace according to claim 2,
The metal melting furnace characterized in that the inner wall surface of the second furnace wall has an inclined surface such that the gap becomes narrower from the upper surface to the lower surface of the second furnace wall.
In the metal melting furnace according to any one of claims 1 to 3,
Between the lower surface of the second furnace wall in the crucible fixing ring and the upper surface of the first furnace wall in the molten metal heat retaining device, a ring-shaped molten metal heat insulating device seal made of a heat-resistant member is laid, The molten metal heat-insulating device seal is laid on the upper surface of the first furnace wall over the entire circumference of the upper surface.
In the metal melting furnace according to claim 4,
The first furnace wall is housed in a metal case;
When the first furnace wall is housed in the metal case, a projecting wall is formed by slightly projecting the upper end side of the metal case from the upper surface of the first furnace wall,
The metal melting furnace is characterized in that the molten metal heat insulating device seal is laid on the upper surface of the first furnace wall so that the outer periphery of the molten metal heat insulating device seal is along the protruding wall.
In the metal melting furnace according to any one of claims 1 to 5,
Between the upper surface of the second furnace wall in the crucible fixing ring and the lower surface of the third furnace wall in the auxiliary ring, a ring-shaped auxiliary ring seal made of a heat-resistant member is laid, and the auxiliary ring The metal melting furnace, wherein the seal is laid over the entire circumference of the upper surface of the second furnace wall.
The metal melting furnace according to claim 6,
A ring in which an opening having an inner diameter equivalent to the outer diameter of the auxiliary ring seal is formed between the upper surface of the second furnace wall in the crucible fixing ring and the lower surface of the third furnace wall in the auxiliary ring. Shaped auxiliary ring seal backing plate is laid,
An auxiliary ring seal guide wall for guiding the laying of the auxiliary ring seal is formed along the edge of the opening at the edge of the opening of the auxiliary ring seal receiving plate. The guide wall has a height lower than the thickness dimension of the auxiliary ring seal;
The metal melting furnace, wherein the auxiliary ring seal is laid on the upper surface of the second furnace wall of the crucible fixing ring so that the outer periphery of the auxiliary ring seal is along the inner periphery of the auxiliary ring seal guide wall .
In the metal melting furnace according to any one of claims 1 to 7,
Between the upper surface of the third furnace wall in the auxiliary ring and the lower surface of the fourth furnace wall in the combustion device, a ring-shaped combustion device seal made of a heat-resistant member is laid, and the combustion device seal Is laid over the entire circumference of the upper surface of the third furnace wall.
The metal melting furnace according to claim 8,
Between the upper surface of the 3rd furnace wall in the said auxiliary ring, and the lower surface of the 4th furnace wall in the said combustion apparatus, the opening part which has an internal diameter equivalent to the outer diameter of the said combustion apparatus seal was formed. Combustion device seal backing plate is laid,
A combustion device seal guide wall for guiding the laying of the combustion device seal is formed along the edge of the opening at the edge of the opening of the combustion device seal receiving plate. The guide wall has a height lower than the thickness dimension of the combustion device seal;
The metal melting furnace, wherein the combustion device seal is laid on an upper surface of the third furnace wall so that an outer periphery of the combustion device seal is along an inner periphery of the combustion device seal guide wall.
In the metal melting furnace according to any one of claims 1 to 9,
A metal melting furnace comprising a crucible upper temperature sensor for detecting the temperature of the opening-side outer wall surface of the crucible.
In the metal melting furnace according to any one of claims 1 to 10,
A metal melting furnace comprising a crucible bottom temperature sensor for detecting the temperature of the bottom outer wall surface of the crucible.
The metal melting furnace according to any one of claims 1 to 11,
A metal melting furnace having a melt temperature sensor for detecting a temperature of a melt held in the crucible.
The metal melting furnace according to any one of claims 1 to 12,
The metal melting furnace, wherein the heater is an electric heater.
In the metal melting furnace according to any one of claims 1 to 13,
A metal melting furnace, further comprising an impurity removing device that can be immersed in the molten metal held in the crucible with at least the combustion device of the combustion device and the auxiliary ring removed.
The metal melting furnace according to claim 14,
The impurity removing apparatus is a rotary degassing apparatus that has a rotating body at a tip portion and generates an inert gas that is microbubbled while the rotating body rotates in the molten metal. Metal melting furnace.
A method for producing a molten metal in a metal melting furnace using the metal melting furnace according to any one of claims 1 to 15,
A molten metal charging step of charging the molten metal into the crucible;
A melting step of dissolving the metal to be melted by a direct fire by a burner of the combustion device;
A molten metal heat retaining step for retaining the molten metal held in the crucible at a predetermined temperature by the heater;
A method for producing molten metal in a metal melting furnace, comprising:
In the molten metal production | generation method in the metal melting furnace of Claim 16,
The melting step includes a “dissolution / heating step in combination with a burner / heater” that is heated by the heater while dissolving the metal to be dissolved by an open flame with the burner,
When the temperature of the predetermined part of the crucible reaches the first set temperature, the process proceeds to the “melting / heating process using a burner / heater together”, and the predetermined part of the crucible in the “melting / heating process using the burner / heater together”. When the temperature reaches a second set temperature higher than the first set temperature, the molten metal generation in the metal melting furnace is shifted from the “melting / heating process using both a burner and a heater” to the molten metal heat retaining process. Method.
In the molten metal production | generation method in the metal melting furnace of Claim 16 or 17,
The method for producing a molten metal in a metal melting furnace further comprising an impurity removing step of removing impurities contained in the molten metal.
The molten metal production method according to any one of claims 16 to 18,
In addition to preparing n (n is an integer of 2 or more) molten metal heat retaining devices with crucible fixing rings in a state where the crucible fixing ring is placed on the molten metal heat retaining device, one auxiliary ring and one combustion device are prepared. And
When the molten metal heat retaining device with the n crucible fixing rings is the first to nth molten metal heat retaining devices with the crucible fixing ring,
The auxiliary auxiliary ring and the combustion device are mounted on the molten metal heat retaining device with the first crucible fixing ring among the molten metal heat retaining devices with the first to nth crucible fixing rings, and the first crucible fixing ring is attached. In the metal melting furnace characterized by performing the molten metal charging step, the melting step, and the molten metal warming step in the molten metal heat retaining device, and sequentially performing the molten metal warming device with the nth crucible fixing ring. Melt generation method.