JP4157616B2 - Casting equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an alloy casting apparatus, and more particularly to a casting apparatus that cools a molten alloy in two stages with a cooling roll and a rotating disk-shaped cooling mold.
[0002]
[Prior art]
For example, alloys containing rare earth metals such as samarium-cobalt alloys and iron-neodymium-boron alloys are attracting attention as materials for high-performance magnets, hydrogen storage alloys, and negative electrodes for secondary batteries. In order to obtain a high performance alloy, it is necessary to cool and solidify the molten metal effectively because it requires a homogeneous crystal structure in which rare earth metals are finely dispersed. Accordingly, various proposals have been made regarding the production method and production apparatus. However, Japanese Patent Application Laid-Open No. 63-317643 discloses a method for preventing coarsening of crystal grains, segregation, and α-Fe residue. In order to cool at a cooling rate of 1000 ° C./second, in Example 1, the thickness of the molten iron / neodymium / boron alloy was cooled by twin copper rolls having a diameter of 300 mmφ rotating inward toward each other in the opposite direction. A method for obtaining a 1.1 mm slab is disclosed.
[0003]
Also, JP-A-5-222488, JP-A-6-84624, and JP-A-8-229641 similarly disclose that a molten iron / neodymium / boron alloy is strip cast, that is, a single roll that rotates forward. A method for producing a quenched slab by pouring hot water from a dish is proposed. For example, JP-A-8-229641 discloses a cushioning material made of alumina or the like that is interposed between the tip of a tundish and a cooling roll to open a gap, and the angle of the tundish nozzle with respect to the cooling roll. A manufacturing method in which the position is within a specific range is disclosed. In Example 1, the gap between the nozzle at the tip of the tundish and the cooling roll is 0.3 mm, and an iron / neodymium / boron alloy is used. The molten metal is poured from a tundish into a water-cooled copper roll having a diameter of 300 mm that rotates at a rotational speed of 130 rpm, and a slab having a thickness of 0.2 to 0.35 mm is obtained.
[0004]
In addition, a casting apparatus of a cooling method completely different from the above is disclosed in Japanese Patent Application Laid-Open No. 5-237635 filed by the present applicant. 4 is a schematic side view showing the configuration of the casting apparatus 40. FIG. 4 is a schematic side view showing the structure of the casting apparatus 40. As shown in FIG. In the vacuum chamber 41, an induction heating type melting furnace 44 is pivotally supported by a support column 42 and supported by a hydraulic cylinder 43 so as to be tiltable. The induction heating coil 46 for heating the melting furnace 44 is fed by a power cable 45. Then, the molten metal to be formed is poured from a tilted melting furnace 44 via a rod 47 to a disk-shaped mold 55 fixed to a rotating water-cooled disk 53 and cooled and solidified. Yes.
[0005]
The water-cooled disc 53 is rotated in a horizontal plane by a vertical rotation shaft 51 extending outwardly through a vacuum seal 52 provided on the bottom wall of the vacuum chamber 41. A sprocket 56 is attached to the rotating shaft 51, and a lower end thereof is supported by a bearing 59 placed on a mount 67. The rotary shaft 51 is rotated by a drive mechanism 61 including a chain 64 wound around a drive motor 62, a speed reducer 63, a sprocket 66 of the speed reducer 63, and a sprocket 56 of the rotary shaft 51. The water-cooled disc 53 is provided with a cooling water passage, and a disc-shaped mold 55 is placed and fixed with bolts so as to close the cooling water passage. 57 is fixed removably.
[0006]
When casting with the casting apparatus 40, the alloy material is charged into the melting furnace 44, and the induction heating coil 46 is energized with a high-frequency alternating current in a vacuum to melt the alloy material and form a molten metal. Then, the melting furnace 44 is tilted by the hydraulic cylinder 43 and poured onto the rotating mold 55 by water cooling. The molten metal is developed on the entire surface by the rotation of the mold 55 and is cooled and solidified. The cast product solidified in the mold 55 is removed from the mold 55 together with the mold frame 57. Therefore, the work is simple without requiring the disassembly of the mold, and the handling and maintenance of the cast product are facilitated.
[0007]
[Problems to be solved by the invention]
Any of the above-described methods of cooling with a twin roll or a single roll is a method in which a molten metal is cooled with a cooling roll and solidified to form a cast piece. In an actual apparatus, the cooling roll vibrates when rotating, and there is a fear that the roll may become wrinkled due to contact between rolls or contact between the tundish and roll. For example, the interval between the tundish and roll is 0. The limit is about 3 mm. Therefore, the thickness of the obtained slab is about 0.3 mm, and since it is single-sided cooling, the cooling rate is different in the thickness direction, and it cannot be avoided that the crystal grain size is not constant.
[0008]
Further, since the casting apparatus 40 shown in FIG. 4 is a method of cooling the molten metal in the rotating disk-shaped mold 55, it takes time until the molten metal is cooled and solidified, and a request for shortening the casting cycle is required. There is a problem that it cannot respond to. In addition, since it is supplied to the mold 55 via the gutter 47, there is a problem that the portion of the mold 55 to which the high-temperature molten metal is supplied is limited and the portion is easily damaged.
[0009]
The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a casting apparatus in which the molten metal is effectively and evenly cooled and the cast product can be easily taken out.
[0010]
[Means for Solving the Problems]
A casting apparatus according to the present invention is a casting apparatus for melting and casting an alloy material containing a rare earth metal in a closed system in a vacuum or an inert gas atmosphere, and a melting furnace for heating and melting the alloy material; A cooling roll that is rotated at a predetermined speed and extends in a foil shape to cool the alloy material into a semi-solid state, and is installed between the melting furnace and the cooling roll, and the molten metal is supplied to the cooling roll to a predetermined thickness. And a rotating disk-shaped cooling mold for solidifying the semi-solid alloy material cooled by the cooling roll.
[0011]
With such a configuration, the molten metal is rapidly cooled by a cooling roll and further cooled by a rotating disk-shaped cooling mold, so that the cooling rate can be controlled, and it is cooled and solidified in a very short time without causing local cooling. A foil-shaped slab is formed, and fine crystals are uniformly formed therein.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a casting apparatus according to an embodiment of the present invention will be specifically described with reference to the drawings.
[0013]
FIG. 1 is a schematic side view showing a configuration of a casting apparatus 10 according to an embodiment. That is, in the vacuum chamber 1, for example, iron, neodymium, or boron constituting an alloy containing rare earth metal is melted in the melting furnace 4, and the resulting molten metal is supplied from the melting furnace 4 to the cooling roll 13 via the tundish 7. Then, it is cooled in one stage to be in a semi-solidified state, and further supplied onto a disk-shaped cooling mold 25 that rotates in a horizontal plane and cooled in two stages to be solidified.
[0014]
The vacuum chamber 1 is evacuated and an inert gas such as nitrogen gas or argon gas is introduced as necessary. The melting furnace 4 is pivotally supported by the support 2 and is tilted by the hydraulic cylinder 3. Iron, neodymium, and boron are charged into the melting furnace 4 at a predetermined rate and are induction-heated. The induction heating coil 6 for heating the melting furnace 4 is fed by a power cable 5. The temperature of the melting furnace 4 is set to 1400 to 1600 ° C. to melt the alloy material. The melting furnace 4 pivotally supported by the support column 2 is rotated from the position indicated by the solid line by the hydraulic cylinder 3 and finally tilted to the position indicated by the alternate long and short dash line, and the molten metal is discharged to the tundish 7.
[0015]
The entire tundish 7 has a heat-insulated box shape made of ceramic. Inside the tundish 7, a downward inclined receiving plate 8 is provided from the front, which is the downstream side, toward the front side. It flows down and reaches the bottom surface 9, flows almost the entire length of the bottom surface 9, and is quantitatively supplied from the downstream end portion to the cooling roll 13. The shape of the tundish 7 is not particularly limited, but as a box shape capable of always storing a certain amount of molten metal, a hot water outlet is provided at the downstream end of the bottom surface, or a downwardly inclined nozzle or a pouring plate is provided. The molten metal is preferably rectified as much as possible and quantitatively supplied to the cooling roll 13.
[0016]
The cooling roll 13 has a water-cooled metal surface, and usually has a diameter of 300 to 400 mmφ, and is rotated forward by being controlled by an inverter, for example, at a rotational speed of 100 to 1000 rpm. Copper is generally used for the cooling surface of the cooling roll 13, but iron may be used. The cooling roll 13 is rotated by a rotating shaft extending to the outside of the side through a first vacuum seal provided on the side wall of the vacuum chamber 1. FIG. 2 is a cross-sectional view of the cooling roll 13, and the rotating shaft 11 is rotated by a first drive mechanism that is pivotally supported outside the vacuum chamber 1 even though not shown. A part of the rotating shaft 11 is a double pipe composed of an inner pipe 11a and an outer pipe 11b, and the cooling water introduced through a water supply joint (not shown) is supplied to the inner pipe by the first cooling water supply means . 11a is supplied into the cooling roll 13, guided to the rectifying plate 14 in the cooling roll 13, flows spirally in the axial direction along the inner peripheral surface, and is discharged from the outer tube 11b. The number of rotations and the water cooling temperature of the cooling roll 13 vary depending on the type of alloy to be cast or the crystal state to be obtained inside the slab, and cannot be specified unconditionally.
[0017]
Then, the alloy that has been cooled in one stage and brought into a semi-solid state is subsequently dropped into a rotating disc-shaped cooling mold 25 that rotates downward, and then cooled in two stages to be solidified and cast. Although the water cooling temperature of the cooling roll 13 can be lowered to solidify the molten metal, in the present invention, the number of rotations and the water cooling temperature are adjusted, and the cooling roll 13 performs one-stage cooling so as to be in a semi-solid state. Depending on the number of rotations of the cooling roll 13 and the water cooling temperature at this time, the molten metal can be brought into a supercooled state.
[0018]
As shown in FIG. 3, the cooling mold 25 is placed so as to close the cooling water passage 24 provided in the water-cooled disc 23 and is fixed by bolts 25 b and water-cooled. An annular mold frame 27 is provided on the peripheral edge of the cooling mold 25 and is fixed by a frame presser 28. The water-cooled disc 23 is rotated in a horizontal plane by a vertical rotating shaft 21 extending outwardly through a second vacuum seal 22 provided on the bottom wall of the vacuum chamber 1. A sprocket 26 is attached to the rotary shaft 21, and a lower end thereof is supported by a bearing 29 mounted on a part of the gantry 37. The rotating shaft 21 is inverter-controlled by a second driving mechanism 31 including a drive motor 32, a speed reducer 33, a sprocket 36 of the speed reducer 33, and a chain 34 wound around the sprocket 26 of the rotating shaft 21, for example, It is rotated at a rotational speed of 0.25 to 2.5 rpm. A part of the rotating shaft 21 is a double tube composed of an inner tube 21a and an outer tube 21b, and cooling water is introduced through a water supply joint 20 fitted around the rotating shaft 21. The second cooling water supply means flows from the inner pipe 21a through the cooling water passage 24 of the rotary disk 23 and returns to the outer pipe 21b to cool the cooling mold 25.
[0019]
The casting apparatus 10 according to the embodiment of the present invention is configured as described above. Next, the operation thereof will be described. That is, when casting an alloy containing a rare earth metal by the casting apparatus 10, for example, iron, neodymium, boron is introduced into the melting furnace 4 at a predetermined composition ratio, the vacuum chamber 1 is evacuated, and then induction heating is performed. By energizing the coil 6 with high-frequency alternating current, each material is heated and melted. When the molten metal is formed, the hydraulic furnace 3 tilts the melting furnace 4 and discharges it to the tundish 7.
[0020]
In the tundish 7 that has been kept warm, the molten metal flows down along the inclined receiving plate 8 and flows along the bottom surface 9, and is supplied to the cooling roll 13 from the tip. Since the cooling roll 13 is rotated forward at a predetermined speed, the molten metal supplied at a predetermined thickness from the tundish 7 is stretched when it contacts the cooling roll 13 and is uniformly cooled in the thickness direction. . At this time, by adjusting the water cooling temperature, the molten metal is cooled one step so as to be in a semi-solidified state without being solidified, and is dropped as it is onto the rotating disc-shaped cooling mold 25 that rotates downward. Depending on the number of rotations of the cooling roll 13 and the water cooling temperature at this time, the molten metal can be dropped in a supercooled state.
[0021]
The alloy that has been cooled in one stage by the cooling roll 13 and in a semi-solid state falls onto the rotating disk-shaped cooling mold 25 and is cooled in two stages and solidified. This semi-solid alloy falls onto the iron / neodymium / boron alloy that has fallen previously and has been solidified, and is cooled, so it is solidified into a foil without being integrated. Further, the state of crystals in the slab of the obtained iron / neodymium / boron alloy can be changed mainly by adjusting the state of single-stage cooling.
[0022]
The casting apparatus 10 according to the embodiment of the present invention is configured and operates as described above. Of course, the present invention is not limited to this, and various modifications can be made based on the technical idea of the present invention.
[0023]
For example, in the present embodiment, induction heating is employed for melting the material of the rare earth-containing alloy in the melting furnace 4, but heating other than induction heating, for example, heating by irradiation with an electron beam or a laser beam, heating by arc discharge, or the like. Can also be adopted.
[0024]
In the present embodiment, water is used as a coolant for cooling the cooling roll 13 and the cooling mold 55, but glycols and oils can be used as the coolant in addition to water.
[0025]
Moreover, in this Embodiment, although copper was employ | adopted for the metal surface of the cooling roll 13, you may use copper and a beryllium alloy with large thermal conductivity other than copper, and tellurium, and adjust the cooling rate of a molten metal. Therefore, stainless steel having a small thermal conductivity coefficient may be used.
[0026]
Further, although not particularly provided in the present embodiment, a cooling inert gas may be sprayed onto the surface of the rotating cooling mold 25.
[0027]
Moreover, in this Embodiment, although the case where the alloy was cast in the casting apparatus 10 was shown, it cannot be overemphasized that the casting apparatus 10 is applied also to a single metal.
[0028]
【The invention's effect】
The present invention is implemented in the form as described above, and has the following effects.
[0029]
The casting apparatus of the present invention once cools the molten metal with a cooling roll that rotates forward, and then cools the second stage with a disk-shaped cooling mold that rotates in a horizontal plane. Therefore, the cooling rate of the molten metal can be adjusted arbitrarily. Further, by adjusting the rotation speed of the cooling roll, the thickness of the molten metal on the cooling roll can be reduced, and cooling can be performed uniformly in the thickness direction of the molten metal. Moreover, since it is obtained as a foil-shaped slab after cooling, handling is extremely easy.
[Brief description of the drawings]
FIG. 1 is a schematic side view of a casting apparatus according to an embodiment.
FIG. 2 is a cross-sectional view of a cooling roll.
FIG. 3 is a cross-sectional view of a cooling mold.
FIG. 4 is a schematic side view of a conventional casting apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Vacuum chamber 4 Melting furnace 7 Tundish 10 Casting apparatus 13 Cooling roll 25 Cooling mold

Claims (4)

A casting apparatus for melting and casting an alloy material containing a rare earth metal in a closed system in a vacuum or an inert gas atmosphere,
A melting furnace for heating and melting the alloy material;
A chill roll that is rotated at a predetermined speed, extends the foil of the alloy material into a foil shape, and cools it to a semi-solidified state ;
A tundish that is installed between the melting furnace and the cooling roll, and quantitatively supplies the molten metal to the cooling roll at a predetermined thickness;
A casting apparatus comprising: a rotating disk-shaped cooling mold for solidifying the semi-solidified alloy material cooled by the cooling roll. The casting apparatus according to claim 1,
A first drive mechanism that is provided outside the closed system and rotates a rotating shaft of the cooling roll;
A first vacuum seal provided between the sealing system and the rotating shaft;
A casting apparatus further comprising first cooling water supply means for supplying cooling water to the inside of the cooling roll through the inside of the rotating shaft. The casting apparatus according to claim 2,
The said cooling roll is a casting apparatus which has the baffle plate which flows the said cooling water spirally in an axial direction along the internal peripheral surface of the said cooling roll. The casting apparatus according to claim 1,
A second drive mechanism that is provided outside the closed system and rotates a rotating shaft of the cooling mold;
A second vacuum seal provided between the sealing system and the rotating shaft;
A casting apparatus further comprising second cooling water supply means for supplying cooling water to the inside of the cooling mold through the periphery of the rotating shaft.

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