JP7355990B2 - Cold crucible melting furnace and its maintenance method - Google Patents

Description

The present invention relates to a bottom tapping type cold crucible melting furnace.

A typical cold crucible melting furnace includes a chamber and a crucible assembled inside the chamber. In the case of a tapping method (so-called bottom tapping method) in which the material to be melted (molten metal) melted inside the crucible is taken out through a tapping nozzle provided on the bottom side of the crucible, the internal space of the chamber is divided into upper and lower parts. In some cases, the crucible is disposed in the upper space, and the lower space is used as a tap space where molten metal is tapped through a tap nozzle.

Generally, a crucible is formed by arranging a plurality of segments made of a highly conductive metal such as copper in a cylindrical shape. Further, an induction coil is provided around the crucible. On the other hand, a funnel-shaped tap nozzle is provided on the bottom plate that closes the bottom side of the crucible, and an induction coil is also provided around the tap nozzle.

In such a configuration, when a material to be melted such as a metal is put into the crucible and a high-frequency current is passed through an induction coil installed around the crucible, an eddy current is generated in the material to be melted inside the crucible. However, the material to be melted is heated and melted by heat generation (induction heating) caused by eddy current. At this time, the material to be melted forms a skull (a solidified layer of molten metal) on the bottom side of the crucible and inside the enlarged diameter portion of the tapping nozzle, while melting. This skull plugs the tapping nozzle, and prevents the melted material melted in the crucible from leaking out of the tapping nozzle. After the material to be melted has sufficiently melted in the crucible, when a high-frequency current is passed through the induction coil installed around the tap nozzle, the skull inside the tap nozzle is melted by induction heating, and the inside of the crucible is heated. Molten metal is tapped into the tap space through the tap nozzle.

Japanese Patent Application Publication No. 2008-545885

In a bottom tapping type cold crucible melting furnace, as the amount of molten metal inside the crucible decreases, it becomes difficult to apply melting power. For this reason, when the molten metal is completely tapped, it is inevitable that skulls remain on the inner wall of the crucible, the top surface of the bottom plate, the inside of the tap nozzle, etc.

If the melting/tapping operation for the next lot is performed with the skull remaining, the remaining skull will come into close contact with the crucible, the bottom plate, or the tap nozzle. Skulls that are in close contact with the inner wall are hardly melted by induction heating. For this reason, stable hot water supply is not performed, and in the worst case, hot water supply may not be possible. Furthermore, if the type of material to be melted is changed in the next lot, the remaining skulls may cause contamination due to the mixing of different metals.

In order to avoid such a situation, the crucible, bottom plate, and tap nozzle should be removed from any skulls attached to them after each melting/tapping operation is completed once or a predetermined number of times. There is a need. Furthermore, these parts exposed to high-temperature environments are easily damaged, and in addition to removing skulls, it is necessary to repair damaged parts, replace parts, etc. as appropriate.

However, each element such as the crucible, bottom plate, tap nozzle, etc. is assembled inside a chamber, and inside the chamber there are cables for connecting the induction coil and high-frequency power supply, and circulating refrigerant to the crucible and bottom plate. The piping for this purpose is complicatedly arranged. For this reason, the above-mentioned maintenance work on crucibles and the like has become extremely difficult, and in order to ensure sufficient maintenance quality, skilled engineers have had to spend a considerable amount of time performing the maintenance work.

Furthermore, as a matter of course, the cold crucible melting furnace cannot be operated during the maintenance work, and as the time required for the maintenance work increases, the operating efficiency of the cold crucible melting furnace deteriorates.

The present invention has been made to solve the above-mentioned problems, and its purpose is to provide a technology that can improve the efficiency of maintenance work in a bottom tapping type cold crucible melting furnace.

In order to achieve the above object, the present invention takes the following measures.

That is, the present invention is a cold crucible melting furnace,
A cylindrical crucible,
a bottom plate that closes the bottom side of the crucible;
a hot water nozzle provided on the bottom plate;
a melting coil disposed around the crucible;
a hot water tap coil arranged around the hot water tap nozzle;
a chamber forming therein a molten metal space in which the crucible is arranged and a tapping space provided below the tapping nozzle;
Equipped with
The crucible, the bottom plate, and the tapping nozzle are integrated as a melting unit,
The melting unit is formed to be detachably attached to the chamber ,
The tapping coil is left on the side of the chamber when the melting unit is removed from the chamber.

Here, "unitized" refers to a state in which a plurality of elements are connected to each other so that they can be handled as one unified component.

According to this configuration, each unitized element, that is, the crucible, the bottom plate, and the tapping nozzle, can be removed from the chamber all at once. If the melting unit removed from the chamber is transported to another location and disassembled to separate the crucible, bottom plate, and tap nozzle, it is possible to remove any remaining skulls from each of these elements, repair damaged parts, and remove parts. Replacement, etc. can be performed easily and in a short time, and maintenance work can be streamlined.

In addition, if you prepare multiple melting units and use them by replacing the used melting units with maintenance-completed melting units, it is possible to use the melting units while the used melting units are undergoing maintenance work. , a cold crucible melting furnace can be operated. By doing so, the operational efficiency of the cold crucible melting furnace can be dramatically increased.

The present invention is a cold crucible melting furnace, comprising:
A cylindrical crucible,
a bottom plate that closes the bottom side of the crucible;
a hot water nozzle provided on the bottom plate;
a melting coil disposed around the crucible;
a hot water tap coil arranged around the hot water tap nozzle;
a chamber forming therein a molten metal space in which the crucible is arranged and a tapping space provided below the tapping nozzle;
an injection nozzle arranged below the hot water tap coil;
an electromagnetic shielding member disposed between the hot water tapping coil and the injection nozzle, and shielding the injection nozzle from a magnetic field formed by the hot water tapping coil;
Equipped with
The crucible, the bottom plate, and the tapping nozzle are integrated as a melting unit,
The melting unit is formed to be detachable from the chamber.

According to this configuration, each unitized element, that is, the crucible, the bottom plate, and the tapping nozzle, can be removed from the chamber all at once. If the melting unit removed from the chamber is transported to another location and disassembled to separate the crucible, bottom plate, and tap nozzle, it is possible to remove any remaining skulls from each of these elements, repair damaged parts, and remove parts. Replacement, etc. can be performed easily and in a short time, and maintenance work can be streamlined.
In addition, if you prepare multiple melting units and use the used melting unit by replacing it with a maintenance melting unit, you can perform maintenance on the used melting unit.
The cold crucible melting furnace can be operated even while nonce work is being performed. By doing so, the operational efficiency of the cold crucible melting furnace can be dramatically increased.
Further , by spraying gas or the like from an injection nozzle toward the molten metal tapped from the tap nozzle, the molten metal can be solidified to generate fine powder (so-called atomization treatment). On the other hand, since this injection nozzle is shielded from the magnetic field formed by the hot water tapping coil by the electromagnetic shielding member, the injection nozzle is not heated by induction by the magnetic field formed by the hot water tapping coil. Therefore, the injection nozzle can be placed sufficiently close to the tapping coil, and the quality of the fine powder produced in the atomization process can be ensured.

Preferably, the cold crucible melting furnace comprises:
a cylindrical protection member provided on the electromagnetic shielding member;
Equipped with
the bottom plate is placed in contact with the protection member,
The hot water tapping coil is arranged in a space surrounded by the electromagnetic shielding member, the protection member, and the bottom plate.

According to this configuration, the tapping coil is less likely to be contaminated by the blowing up of molten metal sprayed with gas from the injection nozzle or the rolling up of fine powder generated in the atomization process. Therefore, a situation in which particles adhere to the hot water tap coil and cause contamination due to the mixing of different metals is less likely to occur. Further, since the occurrence of electric discharge caused by blowing up of molten metal or rolling up of fine powder reaching the vicinity of the tapping coil is also suppressed, stable atomization processing can be performed.

Preferably, in the cold crucible melting furnace,
The hot water tapping coil, the electromagnetic shielding member, and the protection member are:
The lysis unit is left on the side of the chamber when removed from the chamber.

According to this configuration, the melting unit is prevented from increasing in size and weight, and the melting unit can be easily attached/detached and transported.
Preferably, the cold crucible melting furnace comprises:
a supply pipe connected to the bottom plate that supplies a refrigerant;
a discharge pipe connected to the bottom plate for discharging a refrigerant;
Equipped with
Each of the supply piping and the discharge piping,
It is possible to separate and connect at the connection part provided in the middle of its extension,
A piping section on one side that is separated at the connection is included in the melting unit, and a piping section on the other side is left on the side of the chamber when the melting unit is removed from the chamber.
According to this configuration, by separating each of the supply piping and the discharge piping connected to the bottom plate at the connection portion provided in the middle of their extension, a part of the piping can be separated from the melting unit. This prevents the melting unit from increasing in size and weight, and allows the melting unit to be easily attached/detached and transported.

The present invention is also directed to a method for maintaining a cold crucible melting furnace. That is, the maintenance method is
A cylindrical crucible, a bottom plate that closes the bottom side of the crucible, a tapping nozzle provided on the bottom plate, a melting coil arranged around the crucible, and a tapping nozzle arranged around the tapping nozzle. A method for maintaining a cold crucible melting furnace, comprising: a coil; and a chamber forming therein a molten metal space in which the crucible is arranged and a tapping space provided below the tapping nozzle, the method comprising:
The crucible , the bottom plate, a connecting plate connected to the crucible, a supporting member connected to the bottom plate, a connecting column connecting the connecting plate and the supporting member, and the tapping nozzle are integrated into a unit. removing the dissolved lysis unit from the chamber;
attaching a maintained dissolution unit to the chamber;
a step of disassembling the crucible, the bottom plate, and the tapping nozzle of the melting unit removed from the chamber and performing maintenance on them;
Equipped with

According to this configuration, the unitized elements, that is, the crucible, the bottom plate, and the tapping nozzle, are attached to and removed from the chamber all at once, so maintenance work can be streamlined.

However, in the above configuration, the dissolution unit removed from the chamber and the dissolution unit attached to the chamber may be the same or different. That is, a plurality of melting units may be prepared in advance, and after a used melting unit is removed from the chamber, a maintained melting unit other than the used melting unit may be attached to the chamber, The used lysis unit may be removed and maintained, and then the lysis unit may be attached to the chamber.

According to the present invention, maintenance work can be made more efficient.

FIG. 1 is a side sectional view showing the configuration of a cold crucible melting furnace according to an embodiment. FIG. 2 is an enlarged side cross-sectional view showing the vicinity of a tapping nozzle in FIG. 1; FIG. 3 is a side sectional view showing the configuration of the melting unit. FIG. 3 is a side sectional view showing a state in which the dissolution unit is removed from the chamber part. FIG. 5 is an enlarged side sectional view showing the vicinity of the tapping nozzle in FIG. 4;

Embodiments of the present invention will be described below with reference to the drawings.

<1. Overall configuration of cold crucible melting furnace>
The configuration of a cold crucible melting furnace according to an embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a side sectional view showing the configuration of a cold crucible melting furnace CCF according to an embodiment. FIG. 2 is an enlarged side sectional view showing the vicinity of the tapping nozzle 32 in FIG.

The cold crucible melting furnace CCF includes a chamber section 1 , a crucible section 2 , a bottom plate section 3 , a melting coil section 4 , a tapping coil section 5 , an atomizing section 6 , and a tapping coil protection section 7 .

(Chamber part 1)
The chamber section 1 is a container in which a crucible section 2, a bottom plate section 3, a melting coil section 4, a tapping coil section 5, an atomizing section 6, and a tapping coil protecting section 7 are housed. The chamber section 1 includes a chamber main body 11, which is a cylindrical container whose lower end is closed and whose upper end is open, and a lid section (not shown) that is removably attached to the opening at the upper end. Further, a vacuum pump (not shown) is connected to the chamber body 11. When the opening of the chamber body 11 is hermetically closed by the lid, the interior of the chamber body 11 becomes a closed space. In this state, the pressure inside the chamber main body 11 is reduced by the vacuum pump, so that the inside becomes a vacuum space.

A ring-shaped partition plate 12 is provided inside the chamber body 11 in plan view, and the internal space of the chamber body 11 is divided into upper and lower sections by this partition plate 12. The space above the partition plate 12 is a space (melting space) V1 for melting the material to be melted, and the space below the partition plate 12 is a space where the molten metal melted in the melting space is tapped ( (hot water outlet space) V2. In this embodiment, in the tapping space V2, the tapped molten metal is subjected to an atomization process to generate fine particles. As is well known, atomization is a process in which gas is blown onto molten metal to produce fine powder. A portion of the chamber body 11 below the partition plate 12 is provided with an opening/closing structure (not shown) for taking out fine powder and the like generated in the tapping space V2.

A ring-shaped support plate 13 is provided below the partition plate 12 in a plan view. The outer diameter of the support plate 13 is larger than the inner diameter of the partition plate 12, and the inner diameter of the support plate 13 is smaller than the inner diameter of the partition plate 12. Therefore, the support plate 13 is provided so that its inner diameter side portion protrudes inside the partition plate 12. As will be described later, the upper surface of the support plate 13 constitutes a mounting surface on which the melting unit UT is mounted.

(Crucible part 2)
The crucible part 2 includes a cylindrical crucible 21 and a refrigerant circulation mechanism (first refrigerant circulation mechanism) 22 for cooling the crucible 21.

The crucible 21 is made of copper and has a structure (so-called water-cooled copper segment structure) in which a plurality of water-cooled copper segments are combined into which a coolant such as water is circulated. That is, the crucible 21 has a cylindrical shape by arranging a plurality of vertically long water-cooled copper segments having an arc-shaped cross section in the circumferential direction with a slit-like gap between adjacent water-cooled copper segments via an insulating material. It was assembled in. A refrigerant circulation path 211 is formed inside each segment constituting the crucible 21 . The crucible 21 is cooled by the first refrigerant circulation mechanism 22 circulating the refrigerant through the circulation path 211 .

A support portion 212 is integrally provided on the upper end side of the crucible 21 . An annular supply channel and a drainage channel are formed inside the support portion 212 and communicate with the circulation path 211 formed in each segment constituting the crucible 21 . Furthermore, a radially projecting flange portion 213 is provided on the upper side of the support portion 212 and fixed with bolts B1.

The first refrigerant circulation mechanism 22 is a mechanism for circulating refrigerant in the circulation path 211, and includes a supply pipe 221 that supplies the refrigerant to the circulation path 211, and a discharge pipe 222 that discharges the refrigerant supplied to the circulation path 211. Equipped with

The supply pipe 221 has one end connected to a refrigerant supply source and the other end connected to a supply water channel formed inside the support section 212 . Specifically, the other end side of the supply pipe 221 is fixedly supported by the support part 212 by being embedded in the support part 212 in a posture that allows the end to communicate with the supply waterway. Thereby, the other end of the supply pipe 212 communicates with the circulation path 211 formed in each segment constituting the crucible 21 via the supply waterway.

One end of the discharge pipe 222 is connected to a discharge channel formed inside the support portion 212, and the other end is connected to a discharge line. Specifically, the one end side of the discharge pipe 222 is fixedly supported by the support part 212 by being embedded in the support part 212 in a posture that allows the end to communicate with the discharge waterway. As a result, one end of the discharge pipe 222 communicates with the circulation path 211 formed in each segment constituting the crucible 21 via the discharge waterway.

A connection part 223 for separating and connecting the pipes is provided in the middle of the extension of each pipe 221, 222, and each pipe 221, 222 has a part (first part) closer to the crucible 21 than the connection part 223. and the other side portion (second portion) so that they can be separated and connected. An opening/closing valve, a flow rate regulating valve, etc. are inserted in the middle of the second portion of each of the pipes 221, 222.

(Bottom plate part 3)
The bottom plate part 3 includes a flat bottom plate 31 that closes the bottom side of the crucible 21, a tapping nozzle 32 provided on the bottom plate 31, and a refrigerant circulation mechanism (second refrigerant longitudinal passage mechanism) 33 for cooling the bottom plate 31. Equipped with

The bottom plate 31, like the crucible 21, has a water-cooled copper segment structure. That is, the bottom plate 31 has a circular structure in which a plurality of fan-shaped water-cooled copper segments are arranged in the circumferential direction via an insulating material while providing slit-like gaps between adjacent water-cooled copper segments. It is assembled into a plate shape. A refrigerant circulation path 311 is formed inside each segment that constitutes the bottom plate 31 . The second refrigerant circulation mechanism 33 circulates refrigerant through the circulation path 311, thereby cooling the bottom plate 31.

The tapping nozzle 32 is a funnel-shaped member as a whole, and has a cylindrical shape whose diameter does not change over the entire axial direction of the inverted cone-shaped expanding diameter part that increases as it approaches the upper end. The straight parts are connected. The tapping nozzle 32 is inserted into a through hole provided approximately at the center of the bottom plate 31 .

The second refrigerant circulation mechanism 33 is a mechanism for circulating the refrigerant in the circulation path 311 provided in the bottom plate 31, and includes a supply pipe 331 that supplies the refrigerant to the circulation path 311, and a supply pipe 331 that supplies the refrigerant to the circulation path 311. and a discharge pipe 332 for discharging. The supply pipe 331 has one end connected to a refrigerant supply source and the other end connected to the circulation path 311 . Further, the discharge piping 332 has one end connected to the circulation path 311 and the other end connected to the discharge line. A connection part 333 for separating and connecting the pipes is provided in the middle of the extension of each pipe 331, 332, and each pipe 331, 332 has a part (first part) closer to the bottom plate 31 than the connection part 333. and the other side portion (second portion) so that they can be separated and connected. An opening/closing valve, a flow rate regulating valve, etc. are inserted in the middle of the second portion of each of the pipes 331, 332.

The end of each pipe 331, 332 connected to the circulation path 311 and its vicinity are supported in a predetermined position by a support member 334 provided below the bottom plate 31. That is, the support member 334 is a ring-shaped member, and is provided with a water collection groove 3341 that communicates with the circulation path 311 . The ends of each of the pipes 331 and 332 and their vicinity are embedded in or penetrate the support member 334 in positions and postures that allow the ends to communicate with the water collection groove 3341. This support member 334 is arranged at a position such that the water collection groove 3341 communicates with the circulation path 311, and is fixed to the lower surface of the bottom plate 31 with bolts B2 or the like. As a result, each of the pipes 331 and 332 is fixedly supported with respect to the bottom plate 31 while communicating the ends with the circulation path 311.

(Dissolving coil part 4)
The melting coil unit 4 includes a coil (melting coil) 41 provided around the crucible 21 and a power supply device (first power supply device) 42 connected to the melting coil 41. As will be explained later, when high-frequency power is applied from the first power supply device 42 to the melting coil 41, a high-frequency current flows through the melting coil 41, and the temperature of the material to be melted in the crucible 21 is increased by induction heating. and dissolve.

(Bouting hot water coil part 5)
The hot water tapping coil section 5 includes a coil (a hot water tapping coil) 51 provided around the hot water tap nozzle 32 and a power supply device (second power source device) 52 connected to the hot water tap coil 51 . As will be explained later, when high-frequency power is input from the second power supply device 52 to the hot water tap coil 51, the high frequency current flows through the hot water tap coil 51, causing the skull (molten metal (solidified layer) is heated and melted by induction heating. As a result, the molten metal in the crucible 21 is tapped out from the tapping nozzle 32.

(Atomization processing section 6)
The atomization processing section 6 includes an injection nozzle 61 provided below the tapping nozzle 32, an electromagnetic shielding member 62 provided between the tapping coil 51 and the injection nozzle 61, and cooling for cooling the electromagnetic shielding member 62. A mechanism 63 is provided.

The injection nozzle 61 is a nozzle that injects gas at high pressure, and is made of metal such as SUS. The injection nozzle 61 has a ring shape and is provided below the hot water tap nozzle 32 so that its center line is coaxial with the hot water tap nozzle 32 . On the lower surface side of the injection nozzle 61, a plurality of ejection ports 611 that eject gas diagonally downward are arranged in a circumferential direction. Further, a gas supply mechanism (not shown) is connected to the injection nozzle 61 for supplying gas (for example, inert gas such as argon gas) to each injection port 611. Specifically, the gas supply mechanism includes a gas supply source, a pipe connecting the gas supply source to the injection nozzle 61, a valve inserted in the pipe, and the like.

A predetermined target position P is defined at a position on the center line of the injection nozzle 61 and below the injection nozzle 61, and each ejection port 611 of the injection nozzle 61 directs the gas toward this target position P. It's supposed to squirt out. Therefore, the molten metal tapped from the tap nozzle 32 collides with the gas discharged from each spout 611 at this target position P. The molten metal collided with the gas is crushed and solidified, thereby producing fine powder.

The electromagnetic shielding member 62 is a member that shields the injection nozzle 61 from the magnetic field formed by the hot water tapping coil 51, and is provided between the hot water tapping coil 51 and the injection nozzle 61. Specifically, the electromagnetic shielding member 62 is a ring-shaped flat plate member formed of a conductive material (for example, copper) in a plan view, and is located at a position where its center line coincides with the center line of the hot water tapping coil 51. established in Further, the electromagnetic shielding member 62 has an inner diameter smaller than the inner diameter of the injection nozzle 61 and an outer diameter larger than the outer diameter of the injection nozzle 61, so that it is difficult to completely cover the injection nozzle 61 when viewed from above. The size is such that it can be done.

The cooling mechanism 63 is a mechanism for cooling the electromagnetic shielding member 62, and includes a circulation pipe 631, a supply pipe 632 that supplies refrigerant here, and a discharge pipe (not shown) that discharges the refrigerant supplied to the circulation pipe 631. ). The circulation piping 631 is directly provided on the lower surface of the electromagnetic shielding member 62 by, for example, being brazed, so as to be in contact with the lower surface of the electromagnetic shielding member 62 . The supply pipe 632 has one end connected to a refrigerant supply source and the other end connected to the circulation pipe 631. Furthermore, one end of the discharge pipe is connected to the circulation pipe 631, and the other end is connected to the discharge line. An opening/closing valve, a flow rate regulating valve, etc. are inserted in each of the supply piping 632 and the discharge piping.

(Bouting hot water coil protection part 7)
The hot water tap coil protection unit 7 is an element for protecting the hot water tap coil 51, and includes a first protection member 71 and a second protection member 72.

The first protection member 71 and the second protection member 72 are both cylindrical members fixedly provided in a concentric arrangement on the upper surface of the electromagnetic shielding member 62, and are made of various refractories, ceramics such as BN, etc. It is formed by etc. The first protection member 71 is arranged relatively outside, and its outer diameter is less than or equal to the outer diameter of the electromagnetic shielding member 62 and greater than or equal to the outer diameter of the hot water tapping coil 51. On the other hand, the second protection member 72 is arranged relatively inside, and its outer diameter is approximately the same as the inner diameter of the electromagnetic shielding member 62 and is equal to or smaller than the inner diameter of the hot water tapping coil 51.

The bottom plate 31 is arranged so that its lower surface is in contact with the upper end surface of each protection member 71, 72. Therefore, a space (protected space) V21 surrounded by the electromagnetic shielding member 62, the bottom plate 31, and the pair of protection members 71 and 72 is formed, and the hot water tapping coil 51 is arranged in this protected space V21. It is sufficient that the protected space V21 has at least a closed property to prevent particles such as molten metal and fine powder from entering.

<2. Melting unit UT>
In the cold crucible melting furnace CCF, among the elements arranged inside the chamber portion 1, the crucible 21, the bottom plate 31, the tapping nozzle 32, and the melting coil 41 are unitized as a melting unit UT. The melting unit UT is formed to be detachable from the chamber portion 1.

However, here, "unitized" refers to a state in which a plurality of elements are connected to each other so that they can be handled as one unified component.

The configuration of the melting unit UT will be specifically explained with reference to FIGS. 3 to 5. FIG. 3 is a side sectional view showing the configuration of the melting unit UT. FIG. 4 is a side sectional view showing a state in which the dissolution unit UT is removed from the chamber part 1. FIG. 5 is an enlarged side sectional view showing the vicinity of the tapping nozzle 32 in FIG. 4. As shown in FIG.

The crucible 21 and the bottom plate 31 are connected via a connecting plate 81 and a connecting column 82. That is, the connecting plate 81 is a flat plate member having a ring shape in a plan view and having an outer diameter that is approximately the same as the outer diameter of the supporting member 334. are connected using . On the other hand, a plurality of connecting columns 82 are arranged and erected along the circumferential direction on the outer edge side of the support member 334 provided below the bottom plate 31, and the upper end of each connecting column 82 It is connected to the bottom surface using bolts or the like. This connects the crucible 21 and the bottom plate 31. The connection strength between the crucible 21 and the bottom plate 31 may be such that the molten metal does not leak out from the gap between the crucible 21 and the bottom plate 31.

As described above, the tapping nozzle 32 is provided on the bottom plate 31. Further, the melting coil 41 is connected to the bottom plate 31 using bolts B4. Therefore, by connecting the crucible 21 and the bottom plate 31, the crucible 21, the bottom plate 31, the tapping nozzle 32, and the melting coil 41 are integrated into a unit, thereby forming the melting unit UT.

The melting unit UT is placed on the support plate 13 and fixed to the chamber part 1 by being fixed to the support plate 13 using bolts (unit fixing bolts) B5. That is, a bolt insertion hole is provided in a region of the support member 334 that overlaps with the support plate 13 when viewed from above, and a bolt hole is provided at a corresponding position in the support plate 13. The melting unit UT is placed on the support plate 13, and the unit fixing bolt B5 is inserted into the bolt insertion hole of the support member 334, and is screwed into the bolt hole of the support plate 13 and tightened. The UT is fixed to the chamber part 1. With the melting unit UT installed in the chamber portion 1 in this manner, the crucible 21 is placed in the tapping space V1, and the tapping space V2 is provided below the tapping nozzle 32.

<3. Residual unit SUT>
In the cold crucible melting furnace CCF, among the elements arranged in the chamber part 1, the elements that are not unitized as the melting unit UT are a tapping coil 51, an injection nozzle 61, an electromagnetic shielding member 62, and a pair of The protective members 71 and 72 are also unitized as a residual unit SUT. Below, the configuration of the remaining unit SUT will be specifically explained with reference to FIG. 5.

The injection nozzle 61 and the electromagnetic shielding member 62 are connected via a connecting column 83. That is, the upper end of a connecting column 83 is fixed to the lower surface side of the electromagnetic shielding member 62, and the injection nozzle 61 is connected to the connecting column 83 using a bolt B6. As a result, the injection nozzle 61 is arranged below the electromagnetic shielding member 62 in a substantially horizontal position while being spaced therefrom.

As described above, the pair of protection members 71 and 72 are fixedly provided on the upper surface of the electromagnetic shielding member 62. Moreover, the hot water tapping coil 51 is fixed to an electromagnetic shielding member 62. Therefore, by connecting the injection nozzle 61 and the electromagnetic shielding member 62, the injection nozzle 61, the electromagnetic shielding member 62, the pair of protection members 71 and 72, and the hot water tapping coil 51 are integrated into a unit. A residual unit SUT is formed.

The remaining unit SUT is fixed to the chamber part 1 by being fixed to the support plate 13 . That is, the upper ends of the plurality of pillars 84 are fixed near the outer peripheral edge of the lower surface of the electromagnetic shielding member 62. The lower end of each support 84 and the lower surface of the support plate 13 are fixed to the connecting piece 85 with bolts B7, respectively. Thereby, the support plate 13 and the electromagnetic shielding member 62 are connected. That is, the remaining unit SUT is fixed to the chamber part 1. Unlike the dissolution unit UT, the remaining unit SUT is not frequently attached to and detached from the chamber section 1, and basically remains fixed to the chamber section 1.

<4. Operation of cold crucible melting furnace CCF>
Next, the operation of the cold crucible melting furnace CCF will be explained with reference to FIGS. 1 to 5.

(Dissolution treatment process)
In the cold crucible melting furnace CCF, when melting the material to be melted, the material to be melted is put into the crucible 21 and high frequency power is put into the melting coil 41 from the first power supply device 42 . When a high frequency current flows through the melting coil 41, the temperature of the material to be melted in the crucible 21 is increased by induction heating. The material to be melted melts while forming a skull on the bottom side of the crucible 21 and inside the enlarged diameter portion of the tapping nozzle 32. The tapping nozzle 32 is plugged by this skull, and the melted material (molten metal) 9 is prevented from leaking out from the tapping nozzle 32. While this dissolution process is being performed, each refrigerant circulation mechanism 22, 32 circulates the refrigerant through the circulation paths 211, 311. This ensures that the crucible 21 and the bottom plate 31 are not melted, deformed, damaged, etc.

(Atomization process)
When the material to be melted in the crucible 21 is sufficiently melted, high frequency power is supplied from the second power supply device 52 to the hot water tap coil 51 . When a high-frequency current flows through the hot water tapping coil 51, the skull formed in and around the hot water tap nozzle 32 is heated by induction heating and melted. As a result, the molten metal in the crucible 21 is tapped out from the tapping nozzle 32. Almost simultaneously with the start of dispensing molten metal from the dispensing nozzle 32, the injection of gas from the injection nozzle 61 starts. Therefore, the molten metal tapped from the tap nozzle 32 collides with the gas discharged from each spout 61 at the target position P, is crushed and solidified, and becomes fine powder.

As described above, the injection nozzle 61 is shielded from the magnetic field formed by the tapping coil 51 by the electromagnetic shielding member 62. Therefore, in this atomization process, the situation where the injection nozzle 61 is exposed to the magnetic field formed by the tapping coil 51 and heated by induction is avoided. On the other hand, the electromagnetic shielding member 62 can be exposed to the magnetic field formed by the tapping coil 51 and heated by induction. However, while this atomization process is being performed, the cooling mechanism 63 is cooling the electromagnetic shielding member 62. Therefore, in the atomization process, the electromagnetic shielding member 62 is guaranteed not to melt, deform, or be damaged.

In addition, in this atomization process, there is a possibility that the molten metal may blow up or the fine powder may roll up in the tapping space V2. , and the inside of the protected space V21 formed by the bottom plate 31, the tapping coil 51 is not contaminated by molten metal blowing up, fine powder rolling up, etc. In addition, a situation in which discharge occurs due to blown-up molten metal or rolled-up fine powder reaching the tapping coil 51 is also avoided.

(melting unit replacement process)
When the molten metal in the crucible 21 is completely discharged, the injection of gas from the injection nozzle 61 is stopped, and the atomization process is completed. When the molten metal 8 in the crucible 21 is completely tapped, skulls remain inside the crucible 21, the tap nozzle 32, and the like. If the melting process for the next lot is performed continuously in this state, not only will a very large amount of electric power be required to melt the skull remaining inside the tap nozzle 32, etc. In the worst case, the skull may not be sufficiently dissolved, making it difficult to take out the bath. Furthermore, when the type of material to be melted is changed in the next lot, skulls remaining inside the crucible 21 and tapping nozzle 32 may cause contamination due to mixing of different metals. . In order to avoid these situations, the melting unit UT is replaced before the melting process for the next lot is performed.

Specifically, first, the lid section is removed from the chamber body 11, and the used dissolution unit UT is removed from the chamber section 1 and carried out from there. Specifically, first, each of the pipes 221 and 222 of the first refrigerant circulation mechanism 22 is separated at the connecting portion 223 and separated into a first portion and a second portion. Similarly, the pipes 331 and 332 of the second refrigerant circulation mechanism 32 are also separated at the connecting portion 333 and separated into a first portion and a second portion. Further, the connection terminal of the melting coil 41 is removed from the connector of the first power supply device 42 . Further, the unit fixing bolt B5 fixing the melting unit UT to the chamber part 1 is removed. Thereafter, a hook or the like of a lifting device (for example, a crane) is hooked onto the locked portion 811 provided on the top surface of the connecting plate 81 of the melting unit UT, and the lifting device lifts the melting unit UT from the chamber portion 1. It will be carried out.

As a result, each element included in the melting unit UT, that is, the crucible 21, the bottom plate 31, the tapping nozzle 32, the melting coil 41, etc., is removed from the chamber section 1 all together and transported from there. Further, a first portion of the supply piping 221 and the discharge piping 222 of the first refrigerant circulation mechanism 22 that is closer to the crucible 21 than the connecting portion 223 is included in the melting unit UT, and is carried out from the chamber portion 1 together with the melting unit UT. , the second part on the other side is left on the chamber part 1 side. Similarly, a first portion of the supply piping 331 and the discharge piping 332 of the second refrigerant circulation mechanism 33, which is closer to the bottom plate 31 than the connecting portion 333, is included in the melting unit UT, and is carried out from the chamber portion 1 together with the melting unit UT. The second portion on the other side is left on the chamber part 1 side. Further, each element included in the remaining unit SUT, that is, the tapping coil 51, the injection nozzle 61, the electromagnetic shielding member 62, the pair of protection members 71 and 72, etc., is also left on the chamber part 1 side.

When the used melting unit UT is carried out from the chamber section 1, another maintenance-completed melting unit UT is carried into the chamber section 1 and attached thereto. Specifically, first, a hook or the like of a lifting device is hooked onto the locked portion 811 of the other melting unit UT, and the melting unit UT is lifted by the lifting device and carried into the chamber section 1, and the partition plate 12 is placed on top of the At this time, the upper ends of the pair of protection members 71, 72 and the lower surface of the bottom plate 31 in the melting unit UT are brought into contact with each other without providing a gap therebetween. As a result, a protected space V21 is formed, and the hot water tapping coil 51 is housed inside the protected space V21.

Subsequently, the unit fixing bolt B5 is inserted into the bolt insertion hole of the support member 334 and tightened while being screwed into the bolt hole of the support plate 13. Furthermore, the pipes 221 and 222 of the first refrigerant circulation mechanism 22 are connected at the connecting portion 223, so that the first portion and the second portion are in communication with each other. Similarly, the respective pipes 331 and 332 of the second refrigerant circulation mechanism 32 are also connected at the connecting portion 333, so that the first portion and the second portion are in communication with each other. Further, the connection terminal of the melting coil 41 is attached to the connector of the first power supply device 42 . This completes the assembly of the melting unit UT. With the above steps, the replacement of the melting unit UT is completed, and the melting process for the next lot can be started.

Note that the melting unit UT carried out from the chamber section 1 is subjected to maintenance while the processing process related to the next lot is being performed. That is, the melting unit UT carried out from the chamber part 1 is transported to another disassembly site or the like and disassembled. The separated elements, that is, the crucible 21, the bottom plate 31, and the tap nozzle 32, have skulls attached to them removed, damaged parts repaired as necessary, and parts replaced. It can then be reassembled. The melting unit UT that has been maintained in this manner is replaced with a used melting unit UT and reused.

<5. Effect>
In the cold crucible melting furnace CCF according to the above embodiment, the crucible 21, the bottom plate 31, and the tapping nozzle 32 are unitized as a melting unit UT, and the melting unit UT is detachable from the chamber part 1. is formed.

According to this configuration, each element unitized as the melting unit UT, that is, the crucible 21, the bottom plate 31, and the tapping nozzle 32, can be removed from the chamber part 1 all at once. If the melting unit UT removed from the chamber part 1 is transported to another location and disassembled to separate the crucible 21, bottom plate 31, and tapping nozzle 32, the remaining skulls on each of these elements can be removed and damaged. It becomes possible to repair parts, replace parts, etc. easily and in a short time, streamlining maintenance work.

In addition, in the above embodiment, a plurality of melting units UT are prepared, and used melting units UT and maintenance-completed melting units UT are used interchangeably. The cold crucible melting furnace CCF can be operated while the work is being performed. By doing so, the operating efficiency of the cold crucible melting furnace CCF can be dramatically increased.

The cold crucible melting furnace CCF according to the above embodiment also includes a supply pipe 331 connected to the bottom plate 31 for supplying a refrigerant, and a discharge pipe 332 connected to the bottom plate 31 for discharging the refrigerant. . Each of the supply piping 331 and the discharge piping 332 can be separated and connected at a connecting portion 333 provided in the middle of their extension, and the piping portion on one side that is separated at the connecting portion 333 is included in the melting unit UT. The piping section on the other side is left on the side of the chamber part 1 when the melting unit UT is removed from the chamber part 1.

According to this configuration, by separating each of the supply piping 331 and the discharge piping 332 connected to the bottom plate 31 at the connecting part 333 provided in the middle of their extension, a part of the piping can be separated from the melting unit UT. be able to. This prevents the melting unit UT from increasing in size and weight, and allows the melting unit UT to be easily attached/detached and transported.

Further, in the cold crucible melting furnace CCF according to the above embodiment, the injection nozzle 61 is arranged below the tapping coil 51, and the injection nozzle 61 is arranged between the tapping coil 51 and the injection nozzle 61. It includes an electromagnetic shielding member 62 that shields the injection nozzle 61 from the generated magnetic field.

According to this configuration, by spraying gas or the like from the injection nozzle 61 toward the molten metal tapped from the tapping nozzle 32, the molten metal can be solidified and fine powder can be generated. On the other hand, the injection nozzle 61 is shielded from the magnetic field formed by the hot water tapping coil 51 by the electromagnetic shielding member 62, so that the injection nozzle 61 is prevented from being inductively heated by the magnetic field formed by the hot water tapping coil 51. There is no. Therefore, it becomes possible to arrange the injection nozzle sufficiently close to the hot water tapping coil. That is, the target position P can be set to a position close to the discharge port of the hot water tap nozzle 32. The flow of molten metal tapped from the tap nozzle 32 becomes more easily disturbed as it moves away from the discharge port of the tap nozzle 32, but by setting the target position P within a range where a stable flow of molten metal can be obtained, the atomization process can be performed. The quality of the generated fine powder (specifically, the shape, particle size, etc. of the fine powder) can be ensured.

Further, the cold crucible melting furnace CCF according to the above embodiment further includes a cooling mechanism 63 for cooling the electromagnetic shielding member 62.

According to this configuration, even if the electromagnetic shielding member 62 is inductively heated by the magnetic field formed by the tapping coil 51, the temperature does not rise excessively. Therefore, the electromagnetic shielding member 62 is unlikely to be melted, deformed, damaged, etc. by induction heating.

Further, the cold crucible melting furnace CCF according to the above embodiment includes cylindrical protection members 71 and 72 provided on the electromagnetic shielding member 62. The bottom plate 31 is placed in contact with the protection members 71 and 72, and the hot water tapping coil 51 is placed in a protected space V21 surrounded by the electromagnetic shielding member 62, the protection members 71 and 72, and the bottom plate 31. Ru.

According to this configuration, the tapping coil 51 is unlikely to be contaminated by the blowing up of the molten metal to which gas is blown from the injection nozzle 61 or the rolling up of the fine powder generated in the atomization process. Therefore, a situation in which particles adhere to the hot water tap coil 51 and cause contamination due to the mixing of different metals is unlikely to occur.

Furthermore, when tapping hot water, the tapping coil 51 is in a high voltage state, so if the molten metal blows up or the fine powder rolls up and reaches the vicinity of the hot water tapping coil 51, there is a risk that electric discharge will occur. . When discharge occurs, the supply of power to the hot water tapping coil 51 is stopped, and as a result, hot water taping becomes unstable or stopped, making it impossible to stably perform the atomization process. As a result, the quality of the fine powder produced and the production efficiency are reduced. Furthermore, in the worst case, there is a risk that the hot water tap coil and power supply device may be damaged due to the occurrence of electrical discharge. According to the above configuration, the blowing up of molten metal and the rolling up of fine powder do not reach the vicinity of the tapping coil 51, so that the occurrence of electric discharge is suppressed. As a result, stable atomization processing can be performed, and damage to the hot water tapping coil 51 and the second power supply device 52 can also be avoided.

Further, in the cold crucible melting furnace CCF according to the above embodiment, the tapping coil 51, the electromagnetic shielding member 62, and the protective members 71, 72 are installed in the chamber when the melting unit UT is removed from the chamber section 1. Left on the side of part 1.

According to this configuration, the melting unit UT is prevented from increasing in size and weight, and the melting unit UT can be easily attached/detached and transported.

In addition, in the maintenance method of the cold crucible melting furnace CCF according to the above embodiment, the process of removing the melting unit UT, which is a unit of the crucible 21, the bottom plate 31, and the tap nozzle 32, from the chamber part 1, and The method includes a step of attaching the dissolution unit UT to the chamber part 1.

According to this configuration, the elements that are unitized as the dissolving unit UT are collectively attached to and detached from the chamber section 1, so that maintenance work can be streamlined.

<6. Other embodiments>
In the above embodiment, the circulation piping 631 through which the refrigerant for cooling the electromagnetic shielding member 62 is circulated is brazed to the lower surface of the electromagnetic shielding member 62. It may also be provided embedded in.

The elements that are unitized as the melting unit UT are not limited to those exemplified in the above embodiments. For example, at least one of the hot water tapping coil 51, the first protection member 71, the second protection member 72, the electromagnetic shielding member 62, the cooling mechanism 63, and the injection nozzle 61 may be unitized as the melting unit UT. good.

In the above embodiment, the injection nozzle 61 is ring-shaped, but the injection nozzle does not necessarily have to be ring-shaped. For example, a plurality of rod-shaped injection nozzle parts may be arranged in the circumferential direction to form an injection nozzle.

In the above embodiment, the molten metal tapped from the tap nozzle 32 is atomized to generate fine powder, but the tapped molten metal is poured into a mold and a cast product is generated. good. Needless to say, in this case, there is no need to provide the injection nozzle 61.

In the embodiment described above, the hot water tap coil protection section 7 includes a pair of protection members 71 and 72, but the configuration of the hot water tap coil protection section is not limited to this. For example, the hot water tapping coil protection portion may be constituted by a block body made of refractory material, ceramics, etc., and the hot water tapping coil 51 may be entirely buried inside the block body.

In the above embodiment, the first protection member 71 and the second protection member 72 are not essential elements, and at least one of them may be omitted. When an electromagnetic shielding member 62 is provided below the tapping coil 51, the blowing up of the molten metal and the rolling up of fine powder are shielded to some extent by the electromagnetic shielding member 62, so the pair of protection members 71 and 72 are Even if omitted, contamination of the hot water tap coil 51 can be suppressed to some extent.

In the above embodiment, the configuration of the cooling mechanism 63 that cools the electromagnetic shielding member 62 is not limited to that illustrated above. For example, plates made of a magnetic material may be stacked and arranged on the electromagnetic shielding member 62. According to such a configuration, induction heating of the electromagnetic shielding member 62 is suppressed by interposing the plate made of a magnetic material between the hot water tapping coil 51 and the electromagnetic shielding member 62. Therefore, even if the cooling mechanism 63 is not provided, the electromagnetic shielding member 62 can be prevented from being melted, deformed, damaged, etc. by induction heating.

In the above embodiment, the electromagnetic shielding member 62 is not an essential element and may be omitted.

In the above embodiment, the crucible 21 was placed on the bottom plate 31 and indirectly connected to the bottom plate 31 via the connecting plate 81 and the connecting column 82, but the lower end of the crucible 21 was placed on the bottom plate 31. The crucible 21 and the bottom plate 31 may be directly connected by being fixed to the crucible 31 by a fitting structure or the like.

In the embodiments described above, the crucible 21 does not necessarily have to be cylindrical, but may be polygonal. Further, the crucible 21 does not necessarily have to have a straight shape with the same diameter from top to bottom, but may have a tapered shape that widens downward.

In the above embodiment, the melting unit UT may be replaced each time a series of processing steps for one lot is completed, or each time the type of material to be melted is changed. .

In the above embodiment, a plurality of melting units UT are prepared, and a used melting unit UT is replaced with another melting unit UT that has been maintained, but it is not necessarily the case that a plurality of melting units UT does not need to be prepared. In this case, the cold crucible melting furnace CCF cannot be operated while the used melting unit UT is being carried out from the chamber section 1 and subjected to maintenance, so its operating efficiency cannot be greatly improved. However, in this case as well, the work efficiency, reliability, and workability of maintenance work for each element such as the crucible 21, the bottom plate 31, and the tapping nozzle 32 are maintained while these elements are assembled in the chamber part 1. This can be significantly improved compared to the case where the

Other configurations can also be modified in various ways without departing from the spirit of the present invention.

1 Chamber part 11 Chamber body 12 Partition plate 13 Support plate 2 Crucible part 21 Crucible 211 Circulation path 212 Support part 213 Flange part 22 Refrigerant circulation mechanism (first refrigerant circulation mechanism)
221 Supply piping 222 Discharge piping 223 Connection part 3 Bottom plate part 31 Bottom plate 32 Hot water tap nozzle 33 Refrigerant circulation mechanism (second refrigerant circulation mechanism)
331 Supply pipe 332 Discharge pipe 333 Connection part 334 Support member 4 Melting coil part 41 Melting coil 42 First power supply device 5 Hot water tap coil part 51 Hot water tap coil 52 Second power supply device 6 Atomization processing part 61 Injection nozzle 62 Electromagnetic shield Member 63 Cooling mechanism 631 Circulation piping 7 Hot water tap coil protection part 71 Protection member (first protection member)
72 Protective member (second protective member)
9 Material to be melted (molten metal)
CCF Cold Crucible Melting Furnace UT Melting Unit SUT Residual Unit

Claims (6)

A cylindrical crucible,
a bottom plate that closes the bottom side of the crucible;
a hot water nozzle provided on the bottom plate;
a melting coil disposed around the crucible;
a hot water tap coil arranged around the hot water tap nozzle;
a chamber forming therein a molten metal space in which the crucible is arranged and a tapping space provided below the tapping nozzle;
Equipped with
The crucible, the bottom plate, and the tapping nozzle are integrated as a melting unit,
The melting unit is formed to be detachably attached to the chamber,
the tapping coil is left on the side of the chamber when the melting unit is removed from the chamber;
Cold Crucible Melting Furnace. A cylindrical crucible,
a bottom plate that closes the bottom side of the crucible;
a hot water nozzle provided on the bottom plate;
a melting coil disposed around the crucible;
a hot water tap coil arranged around the hot water tap nozzle;
a chamber forming therein a molten metal space in which the crucible is arranged and a tapping space provided below the tapping nozzle;
an injection nozzle arranged below the hot water tap coil;
an electromagnetic shielding member disposed between the hot water tapping coil and the injection nozzle, and shielding the injection nozzle from a magnetic field formed by the hot water tapping coil;
Equipped with
The crucible, the bottom plate, and the tapping nozzle are integrated as a melting unit,
The melting unit is formed to be detachable from the chamber.
Cold Crucible Melting Furnace. The cold crucible melting furnace according to claim 2 ,
a cylindrical protection member provided on the electromagnetic shielding member;
Equipped with
the bottom plate is placed in contact with the protection member,
The hot water tap coil is arranged in a space surrounded by the electromagnetic shielding member, the protection member, and the bottom plate.
Cold Crucible Melting Furnace. The cold crucible melting furnace according to claim 3 ,
The hot water tapping coil, the electromagnetic shielding member, and the protection member are:
remaining on the side of the chamber when the lysis unit is removed from the chamber;
Cold Crucible Melting Furnace. The cold crucible melting furnace according to any one of claims 1 to 4 ,
a supply pipe connected to the bottom plate that supplies a refrigerant;
a discharge pipe connected to the bottom plate for discharging a refrigerant;
Equipped with
Each of the supply piping and the discharge piping,
It is possible to separate and connect at the connection part provided in the middle of its extension,
a piping section on one side that is separated at the connection is included in the melting unit, and a piping section on the other side is left on the side of the chamber when the melting unit is removed from the chamber;
Cold Crucible Melting Furnace. A cylindrical crucible, a bottom plate that closes the bottom side of the crucible, a tapping nozzle provided on the bottom plate, a melting coil arranged around the crucible, and a tapping nozzle arranged around the tapping nozzle. A method for maintaining a cold crucible melting furnace, comprising: a coil; and a chamber forming therein a molten metal space in which the crucible is arranged and a tapping space provided below the tapping nozzle, the method comprising:
The crucible , the bottom plate, a connecting plate connected to the crucible, a supporting member connected to the bottom plate, a connecting column connecting the connecting plate and the supporting member, and the tapping nozzle are integrated into a unit. removing the dissolved lysis unit from the chamber;
attaching a maintained dissolution unit to the chamber;
a step of disassembling the crucible, the bottom plate, and the tapping nozzle of the melting unit removed from the chamber and performing maintenance on them;
A maintenance method for a cold crucible melting furnace.

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