JP2007136543A - Cooling apparatus, strip casting apparatus and method for cooling alloy cast sheet for niobium-based sintered magnet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling apparatus which can change its cooling capacity in order to optimize the structural control and particularly, can lower the cooling capacity in a high temperature range without degrading the cooling capacity in a low temperature range which affects the cooling time; and further, to provide a strip casting apparatus for alloy of a niobium-based sintered magnet provided with such cooling apparatus; and to provide a method for cooling the cast sheet of the above alloy. <P>SOLUTION: Plurality of fins are arranged in the inside of a cylindrical rotating body rotatable in the normal and the reverse directions as the rotating direction, and covers are arranged so as to cover these fins. In the case of rotating the rotating body in the normal direction, the covers are constituted so as not to bring the cast sheet into contact with the fins and the inner surface of the rotating body by pushing out the cast sheet, Also, in the case of rotating this rotating body in the reverse direction, the covers are constituted so as to come into contact with the fins and the inner surface of the rotating body by taking in the cast sheet from an opening hole part arranged at the front surface. The cooling speed can be varied by changing the normal and the reverse rotating directions of the rotating body. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a casting flake cooling device and a cooling method in a strip casting method, which is a raw material alloy production method for neodymium iron boron-based sintered magnets, and in particular, a cooling rate in a high temperature region of a cast flake immediately after falling off a roll. The present invention relates to a cooling device and a cooling method that can change the temperature.

In recent years, demand for high performance neodymium iron boron based sintered magnets (hereinafter referred to as neodymium based magnets) has increased along with the improvement in performance and downsizing of electronic devices such as personal computers and peripheral devices. In addition, for the purpose of reducing the power consumption of home appliances such as air conditioners and refrigerators, or for more efficient motors including hybrid type electric vehicles, there is a demand for neodymium magnets in these fields. It has increased.
On the other hand, the characteristics of neodymium magnets are also improving. Technology for improving characteristics can be broadly divided into two. One of them is related to the structure control of the raw material alloy. The other is related to improvement of magnet manufacturing technology.

In order to improve the characteristics of the magnet, it is important not only to improve the manufacturing process of the magnet, but also to improve the manufacturing technology of the magnet alloy as a raw material.
For example, in the case of a neodymium magnet, which has the highest production volume among rare earth magnets due to its characteristics and economy, the Nd ₂ Fe ₁₄ B phase, which plays a role in magnetism, It is produced from the phase by peritectic reaction. Therefore, in particular, a magnet alloy having a higher stoichiometric composition of the higher-performance Nd ₂ Fe ₁₄ B phase is more likely to generate a primary γFe phase during melt casting. And since this γFe phase is formed in a dendritic form and is three-dimensionally connected, the ingot crushability is significantly impaired, and the particle size distribution of the powder obtained during pulverization in the magnet manufacturing process is excessively widened or the cause of compositional deviation It becomes.

In order to avoid such a problem, recently, a strip casting method (hereinafter referred to as SC method) that can increase the solidification rate at the time of casting has been adopted (see, for example, Patent Document 1). For example, as shown in FIG. 9, in the SC method, molten metal melted in a crucible 72 using high-frequency induction heating in a melting chamber 70 in an inert atmosphere is guided to a water-cooled roll 73 through a tundish 78, and has a thickness of about This is a method of obtaining a cast flake 9 (hereinafter referred to as SC material) of about 0.3 mm. The SC material 9 enters the storage container 79 after being finely crushed by the crusher 76. The storage container 79 containing the SC material 9 is transferred to the cooling chamber 80 using the transport roll 81 and cooled. In FIG. 9, 74 is a molten metal bowl, and 75 is a gate valve.
Since the SC material is thin, the cooling rate in the vicinity of the freezing point becomes about 1000 ° C./s or more, and the Nd ₂ Fe ₁₄ B phase of the magnetic phase is directly from the liquid phase without forming the primary γFe phase. An ingot having no αFe phase formed can be obtained (γFe phase transforms to αFe phase with decreasing temperature and exists as αFe phase in the cooled alloy). Furthermore, an excess of Nd exists as an Nd-rich phase than the Nd ₂ Fe ₁₄ B phase contained in the alloy.

The Nd-rich phase contained in the SC material is finely distributed because the solidification rate is higher than that of an ingot having a thickness of about 30 mm obtained by a conventional casting method using a normal mold. The Nd-rich phase becomes a liquid phase during sintering in the magnet manufacturing process, and promotes an increase in density by so-called liquid phase sintering. Further, in the magnet after sintering, the Nd ₂ Fe ₁₄ B magnetic phase is magnetically blocked, which contributes to an improvement in coercive force. Therefore, it is known that if the Nd-rich phase is more finely and uniformly distributed in the raw material alloy, the dispersion distribution state is improved even in the state of fine powder pulverized in the magnet manufacturing process, which is useful for improving the magnetic properties.

By the way, in general, neodymium magnets are doped with rare earth elements such as Dy and Pr in addition to Nd from the viewpoint of improving heat resistance and economy. Further, in some cases, part of Fe is substituted with Co or other transition metal elements effective in raising the Curie point and improving the corrosion resistance. Therefore, hereinafter, R is used instead of Nd, and T is used instead of Fe, and the Nd ₂ Fe ₁₄ B phase is expressed as an R ₂ T ₁₄ B phase, and the Nd rich phase is expressed as an R rich phase.

The behavior of the R-rich phase in the SC material during casting will be described in more detail.
Upon cooling on a water-cooled roll, the R-rich phase is discharged from the solidification interface along with the growth of the main phase R ₂ T ₁₄ B phase, and is formed in a lamellar form within the R ₂ T ₁₄ B phase crystal grains. Parts are also generated at grain boundaries.
For example, in the Nd—Fe—B ternary equilibrium diagram, the R-rich phase has a melting point of about 660 ° C., which is considerably lower than the liquidus surface temperature of the magnet composition alloy. On the other hand, under normal SC casting conditions, the average temperature when the SC material is detached from the water-cooled roll is 700 ° C. or higher, and the R-rich phase is still in the liquid phase.
In general, the diffusion of atoms in or through the liquid phase is orders of magnitude faster than the diffusion phenomenon in the solid phase. Therefore, the form of the R-rich phase in the SC material varies greatly depending on the cooling rate of the SC material after separation from the water-cooled roll.

  When the cooling rate is slow, the R-rich phase tends to reduce the interfacial energy with the parent phase, and the lamella shrinks and becomes rounded. As the temperature decreases, the R concentration in the R-rich phase increases and the volume ratio of the R-rich phase also decreases. On the other hand, when the cooling rate is high, the tendency that the higher temperature state immediately after the separation from the roll is frozen as it is becomes stronger. That is, the state of the lamella immediately after solidification is maintained as it is, and the secondary lamella is clearly recognized in addition to the primary lamella in the cross-sectional structure of the SC material. In such a case, the volume ratio of the R-rich phase is large and the R concentration in the R-rich phase is low.

  In such a state, for example, when the cross-sectional structure of the SC material is observed with a reflection electron beam image with a scanning electron microscope, a line segment of length L is drawn on the obtained micrograph (composition image), and the line segment is Nd. It can be quantitatively evaluated by counting the number N of points intersecting the rich phase, dividing the length L of the line segment by N, and determining the average interval L / N of the R rich phase, that is, the line segment method. . And this value becomes small, so that the cooling rate after SC material detaches | leaves from a water cooling roll is quick.

Thus, if the presence state of the R-rich phase changes, it will affect the hydrogenation and pulverization processes of the magnet manufacturing process as described below, and the shrinkage behavior during vacuum sintering in the magnet manufacturing process and the magnets obtained. It will also affect the properties.
When producing a sintered magnet, a hydropulverization treatment (HD treatment) is generally performed before fine pulverization using a pulverizer such as a jet mill. The R ₂ T ₁₄ B-based magnet alloy absorbs hydrogen, particularly the R-rich phase easily absorbs hydrogen and forms a hydride and expands in volume. Therefore, the wedge effect and embrittlement due to hydrogenation are combined. Fine cracks are generated in the alloy. For this reason, if the cooling rate after separation from the water-cooled roll is fast and the interval between the R-rich phases is narrow, it tends to break down more easily. When the average particle size of the pulverized powder particles becomes too small, the powder becomes more active and easily burns in the atmosphere, or the oxygen concentration harmful to the magnetic properties of the obtained magnet tends to increase. In addition, the finer the powder, the easier it is to lower the degree of orientation during magnetic field molding, and the more likely to cause problems such as a decrease in magnet characteristics, particularly magnetization.

For this reason, alloys that are rapidly cooled immediately after the SC material is detached from the water-cooled roll tend to be generally unfavorable as a raw material alloy for magnets. In particular, when the cooling rate is too fast, the R concentration in the R-rich phase is too low, and the hydrogenation reaction is difficult or too slow, which may cause a problem in the production process.
However, when magnetic field molding and vacuum sintering are performed using powder with a finer particle size distribution, a magnet with a finer particle size distribution can be obtained, and a magnet with a larger coercive force can be easily manufactured. Therefore, for example, an SC material having a small interval between R-rich phases is suitable as a high-coercivity magnet raw material alloy used for motors and the like. However, in this case as well, as described above, it is not appropriate that the cooling rate is too fast, and the secondary lamella of the R-rich phase is moderately cooled by cooling the high-temperature region after leaving the water-cooled roll at an appropriately slow cooling rate. The SC material with the lost structure is more suitable.

  On the other hand, when the cooling rate of the SC material after separation from the water-cooled roll is slow, the R-rich phase interval becomes wide, and the average particle size of the pulverized particles after the fine pulverization treatment tends to increase. In that case, it is easy to increase the degree of orientation during magnetic field orientation. For example, when producing a magnet with a large magnetization used for a voice coil motor (VCM) that is a head actuator for a hard disk drive (HDD), such a structure is used. Alloys tend to be preferred.

As described above, in the SC method, it is necessary to control the distribution state of the R-rich phase that has an important influence on the magnet characteristics, and for that purpose, it is important to control the cooling conditions after the SC material is detached from the water-cooled roll. Become. In particular, temperature control in a high temperature range (approximately 800 ° C. to 600 ° C.) near the melting point of the R-rich phase after the SC material is detached from the water-cooled roll is important.
As an example of controlling the cooling conditions after the SC material roll is separated, the cooling on the water-cooled roll is divided into the primary cooling and the cooling of the SC material after the separation from the water-cooled roll is divided into the secondary cooling. In order to control, a method of cooling at a cooling rate of 50 ° C./min to 2 × 103 ° C./min below the solidus temperature of the alloy (solidification completion temperature = ternary eutectic temperature) is disclosed (for example, patent) Reference 2).

  The secondary cooling in the technique disclosed above is "inert gas cooling between argon quenching roll and slab storage box, or cooling while being transferred by conveyor or belt, or slab storage. It can be adjusted by cooling with an inert gas in the box, and there are methods such as cooling by sandwiching the slab by two pairs of rotating belts, or directly injecting into liquid argon. It may be a combination. " However, when controlling the cooling rate in the high temperature region, if the same method is used to cool to the low temperature region, the cooling becomes slower as the temperature difference becomes smaller, and even if the SC material is taken out from the chamber, the temperature is lowered to a temperature at which no problem occurs. It takes a long time. No specific means for solving such problems is disclosed at all.

On the other hand, a method is also disclosed in which the average cooling rate between 800 and 600 ° C. is 1.0 ° C./second or less to widen the R-rich phase interval to 3 to 15 μm (see, for example, Patent Document 3).
For such a purpose, immediately after flowing a molten metal of a rare earth element-containing alloy in a vacuum or in an inert gas atmosphere on a cooled rotating roll, and cooling and solidifying the ribbon, the solidified ribbon A structure control method for a rare earth element-containing alloy, characterized in that the crushed alloy piece is stored in a storage container placed in the chamber and the cooling rate of the crushed alloy piece is controlled by a cooling medium. As a specific method, a cooling partition plate is provided inside the storage container, and gas or liquid is circulated as a cooling medium therein to control the cooling rate of the crushed alloy pieces. An alloy structure control method has been proposed (see, for example, Patent Document 4).

  However, in this method, when a gas is used as the cooling medium, the heat capacity per volume of the gas is extremely small, and thus it is necessary to flow a large amount of gas. When an inert gas is used as the gas, it can flow directly between the deposited SC materials, but anyway, heat exchange with a sufficiently wide heat transfer area around a large-diameter pipe to recover and cool the heated gas A vessel is required, and the equipment becomes large. Moreover, the time required for cooling also becomes long.

  Although an example using air as a gas is also shown, in that case, it is necessary to provide a partition plate having a sealed structure. However, the heat capacity per volume of air is small, and in order to increase the cooling rate, a partition plate having a very large heat transfer area capable of flowing a large amount of air is required, and the SC material is accommodated in the gap. . Therefore, the storage container becomes considerably large especially in a mass production scale device. Furthermore, it is necessary to have a movable structure in order to uniformly store the SC material falling into or out of the casting chamber or from the water-cooled roll into the container. It is difficult to send them in terms of equipment reliability. In particular, rare earth-containing alloys are chemically extremely active, and there is a serious problem in terms of safety as an apparatus that handles such active alloys and SC materials having a large specific surface area at high temperatures.

  Further, when water is used as a cooling medium, if it is flowed after casting, water is directly flowed into a partition plate in a high temperature state, which causes a sudden boiling phenomenon, which is problematic in terms of safety. Furthermore, the thermal shock to the partition plate is too large, causing cracks and deformation due to thermal distortion, and there is a problem in terms of durability of the partition plate. In particular, if it breaks, the leaked water reacts with the high-temperature SC material to generate hydrogen, causing serious safety problems. In order to avoid such a problem, when water is flowed before the start of casting, the cooling capacity is too large, and it is difficult to achieve the intended slow cooling condition in a high temperature range.

  In addition, a method is disclosed in which a storage container containing SC material is moved to an adjacent separate chamber and cooled therewith using an inert gas or the like (see, for example, Patent Document 5). In this method, cooling in the high temperature region is generally slow. However, this cooling method is not intended to control the structure of the alloy, and it is impossible to adjust the cooling rate. In addition, the cooling in the low temperature region is slow, and it takes a long time to lower it to a temperature at which it can be opened to the atmosphere. Therefore, a large number of storage containers are required.

In addition, a method for heat-treating the SC material to optimize the structure as a magnet raw material alloy has also been proposed (see, for example, Patent Documents 6 and 7). However, in order to heat-treat an R ₂ T ₁₄ B-based magnet alloy containing an active rare earth element, a vacuum inert atmosphere heat treatment furnace is required, and equipment costs, power costs, and other expensive inert gases such as argon gas are required. Considering the need for gas consumables, this is not an economical method.

  In order to solve the problems described above, the applicant uses a triple-pipe cooling pipe unit composed of an outer pipe, an inner pipe, and an inner pipe, and puts a cooling medium in the path constituted by the inner pipe and the inner pipe. A cooling device was proposed in which the cooling capacity is controlled by changing the temperature of the annular gap between the outer pipe and the middle pipe by introducing vacuum exhaust or helium for promoting cooling (see Patent Document 8).

  Furthermore, as another method, a cylindrical rotating body divided into an anterior chamber and a posterior chamber is used, and the anterior chamber where the SC material first stays and passes is covered with a thin plate so that the cooling rate can be reduced. We proposed a device that can control the alloy structure by moving the SC material from the anterior chamber to the posterior chamber by the action of inclined fins attached to a thin plate covering the anterior chamber by changing the direction of rotation of the body (Patent Document) 9).

The present invention further improves the cooling device using the cylindrical rotating body. The main point of the improvement is to simplify and miniaturize the device and further improve the durability. At the same time, it focuses on expanding the control range of the alloy structure.
JP-A-63-317643 Japanese Patent Laid-Open No. 8-269634 JP-A-10-36949 JP 2002-266006 A JP-A-9-155507 Republished WO2003 / 001541 JP-A-8-264363 JP 2005-021957 A JP 2005-193295 A

  As described above, in the SC method of an alloy for neodymium magnets, in addition to the cooling rate on the water-cooled roll, the temperature at which the R-rich phase is melted after the SC material is detached from the water-cooled roll, particularly immediately after the separation. It is important to control the cooling rate in the region, and this temperature range is moderately slow, and the structure of the alloy is controlled according to the required characteristics of the magnet. In order to increase it, an apparatus and a method that can cool in a short time are required. Moreover, it is a device that handles extremely rare earth alloys that are extremely active and have a large specific surface area, and it is necessary not only to control the structure, but also to provide equipment that fully considers thermal stress, distortion, corrosion, etc., from the viewpoint of safety. There is.

  The present invention proposes a cooling device and a cooling method that can control the cooling conditions freely and that is compact and highly safe, particularly when performing optimum structure control as a raw material alloy for high-performance neodymium magnets. With the goal.

  In the present invention, in order to achieve the above-mentioned problems, the structure controlled cooling device for the SC material in the SC method of the neodymium-based magnet alloy is configured as described below.

  That is, the cooling device according to claim 1 is a device for receiving and cooling the flake-like SC material after being detached from the roll from one side in a strip casting device (hereinafter referred to as SC device) of an alloy for rare earth magnets. A plurality of fins are provided inside a rotating body that is cylindrical and whose direction of rotation is variable in the forward and reverse directions, and a cover is provided so as to cover the fins. Is configured so that the SC material does not contact the fin and the inner surface of the rotating body. On the other hand, when the rotating body is rotated in the opposite direction, the SC material is taken in and the SC material contacts the fin and the inner surface of the rotating body. Thus, the cooling device is configured to have an opening on the front surface on the reverse rotation side.

  During normal rotation, the SC material does not contact the inner surface of the rotating body and the fins, so the cooling rate is slow. During reverse rotation, the SC material is taken inside the cover and contacts the inner surface of the rotating body and the fins, so that cooling is accelerated. . Further, the SC material taken inside the cover is lifted with the rotation of the rotating body, and starts to fall around the uppermost point. For this reason, the contact time becomes longer and the cooling is accelerated. At the same time, since the SC material does not stay inside the cover and is renewed, the entire SC material is uniformly cooled.

  The cooling device according to claim 2 is characterized in that the outside of the rotating body is water-cooled. By cooling with water, the cooling rate during rotation in the reverse direction can be increased, and the time until removal from the chamber can be shortened, thereby increasing productivity.

  The cooling device according to claim 3 is characterized in that the total weight of the rotating body and the fin is set to be not less than 5 times and less than 10 times the weight of the SC material to be cooled. By adopting a structure capable of cooling only by the heat capacity of the rotating body and the fins, water cooling is unnecessary and the structure is simplified. In addition, maintenance of facilities is easy because water is not used. In particular, it is suitable as a cooling device for a small SC device with a small amount of melt casting.

The cooling device according to claim 4, wherein the fin is joined by welding or brazing along the circumference of the rotating body while maintaining an interval of 20 mm to 100 mm over substantially the entire length in the major axis direction of the rotating body. It consists of the metal plate arrange | positioned in multiple steps along the rotation direction of a body.
By disposing the fins in this manner, the heat transfer area can be increased, and the apparatus can be easily manufactured and constructed and has sufficient high-temperature strength.

The cooling device according to claim 5, wherein the cover is made of a metal plate, one end of the metal plate along the longitudinal direction of the rotating body is fixed to the inner surface of the rotating body, and the other end of the metal plate is It is characterized by being released toward the inside of the rotating body.
By being made of metal, both strength and workability can be achieved. Moreover, it becomes easy to fix to a rotary body by methods, such as welding brazing.

The cooling device according to claim 6 is characterized in that an end of the cover that is released toward the inside of the rotating body is bent toward the center of the rotating body.
By doing so, it is easy to prevent the SC material from spilling and entering the inside of the cover during forward rotation, and to easily take the SC material into the cover during reverse rotation.

In the cooling device according to claim 7, in the cross-sectional view along the longitudinal direction of the rotating body, the cover includes three or more and ten or less fins as one unit, and is welded and fixed to the end portions of the fins at both ends. It is characterized by being curved outwardly in a convex shape.
By comprising in this way, the intensity | strength with respect to the weight of SC material increases, and also the durability with respect to the thermal strain and thermal fatigue accompanying a heating improves.

  The cooling device according to an eighth aspect is characterized in that the cover is configured to cover 3 to 10 fins as a unit and also cover the outside of the fins at both ends thereof. Also by comprising in this way, the intensity | strength with respect to the weight of SC material can be increased, and also the durability with respect to the thermal strain accompanying a heating and a thermal fatigue can be improved.

The cooling device according to claim 9 is characterized in that, in such a cooling device, a gap between the fin release end and the cover inner surface is 10 mm to 30 mm. .
By setting the gap between the open end of the fin and the inner surface of the cover in such a numerical range, there is an effect of preventing the SC material from being caught in the gap between the two and becoming difficult to separate.

The cooling device according to claim 10 is configured such that a part of the cooling device that is not covered with the cover on the outer side and the inner surface of the rotating body is covered with one or more metal thin plates. Features.
By doing in this way, it becomes possible to reduce the heat transfer from SC material at the time of forward rotation to a cover or a rotary body, and a cooling rate can be made small.

The cooling device according to an eleventh aspect is characterized in that portions of the outer side of the cover and the inner surface of the rotating body that are not covered with the cover are spray-coated with ceramics.
Ceramics have low thermal conductivity, and it is possible to easily improve heat insulation by covering with a ceramic coating by a method such as plasma spraying.

The cooling device according to claim 12 is configured by spraying ceramics on a portion of the outer side of the cover and the inner surface of the rotating body that is not covered with a cover, and further covering with one or more metal thin plates. And
By covering with a thin metal plate in addition to the ceramic sprayed coating, it is possible to further improve the heat insulation during forward rotation of the rotating body.

The cooling device according to a thirteenth aspect is characterized in that the angle formed by the rotating shaft of the rotating body and the horizontal plane is variable.
By changing the angle that the rotation axis makes with the horizontal plane, the SC material is brought close to one side and gathered, so that the cooling can be slowed or uniform in the direction of the rotation axis, and the cooling rate can be increased. By changing the angle in this way, the cooling rate can be controlled. Further, after the cooling is completed, the SC material can be easily taken out by rotating the entrance side down to improve workability.

The cooling device according to claim 14 is characterized in that an electric heater is disposed at the position of the central axis of the rotating body.
By energizing and heating before the start of casting and preheating the inner surface of the rotating body, the cooling rate of the SC material, particularly immediately after the start of casting, can be reduced.

  A fifteenth aspect of the present invention is an SC device for an alloy for neodymium magnets having such a cooling device. By using such an SC apparatus, it is possible to reduce the cooling rate of the SC material during or after casting and to control the distribution state of the R-rich phase. Moreover, it is possible to increase the cooling rate and increase the productivity by a simple operation such as changing the rotation direction of the rotating body of the cooling device.

The SC material cooling method according to claim 16 uses the SC device provided with the cooling device according to any one of claims 1 to 12 to start casting with the rotating body in a normal rotation state, and for a predetermined time after completion of casting. It is a cooling method of the alloy SC material for neodymium-type magnets which switches the rotation direction of a rotary body and rotates it in a reverse direction after progress.
When the rotator is in a normal rotation state, the SC material does not directly touch the cooling fins or the inner surface of the rotator, so that the SC material can be kept for a longer time in a high temperature range where the cooling rate is slow and the structure changes easily. After a predetermined time has elapsed after the casting is finished, the rotation direction of the rotating body is switched and rotated in the reverse direction, whereby the SC material is taken into the inside of the cover, and directly touches the fins and the inner exposed portions of the rotating body, and is rapidly cooled. .
Thus, the cooling rate can be changed by a simple operation such as changing the rotation direction of the rotating body of the cooling device. Furthermore, by changing the timing for switching the rotation direction of the rotating body, the distribution state of the R-rich phase is changed, and the desired structure can be easily built.

A cooling method according to claim 17 is a method for cooling an alloy SC material for a neodymium-based magnet using an SC device provided with a cooling device in which an angle formed by a rotation axis of the rotating body with respect to a horizontal plane according to claim 13 is variable. It is. Casting is started so that the receiving shaft side is lower than the horizontal plane, and after a predetermined time has elapsed after the start of casting, the inclination of the rotating shaft is horizontal or the receiving side is higher than the horizontal surface, and further, a predetermined time after the end of casting. The rotating direction of the rotating body is switched to the reverse direction after the passage.
By starting the casting so that the receiving shaft side is lower than the horizontal plane, the SC material can be stored on the receiving side, so that the heat radiation effect can be reduced and the cooling can be further slowed down. This makes it easy to build the desired organization.

The cooling method according to claim 18 energizes the electric heater using the SC device including the cooling device in which the electric heater according to claim 14 is arranged, and energizes the rotating body immediately before starting casting in the forward rotation state. Is stopped, and after a predetermined time has elapsed after the end of casting, the rotating direction of the rotating body is switched and rotated in the reverse direction.
By energizing the electric heater before the start of casting and preheating the inner surface of the rotating body, the cooling rate of the SC material, particularly at the beginning of casting, can be further reduced.

A cooling method according to claim 19 is for a neodymium-based magnet using an SC device in which the angle formed by the rotating shaft of the rotating body and the horizontal plane is variable in the cooling device in which the electric heater according to claim 14 is arranged. This is a method for cooling an alloy SC material. After energizing the electric heater, stop energization immediately before the start of casting, start casting with the rotating body in the normal rotation direction and the rotating shaft lower than the horizontal plane on the receiving side, and after a predetermined time has passed, The inclination is set to be horizontal or the receiving side is higher than the horizontal plane, and after a predetermined time has elapsed after the end of casting, the rotating direction of the rotating body is switched and rotated in the reverse direction.
In addition to the preheating effect by the electric heater, starting the casting so that the receiving shaft side is lower than the horizontal plane, the SC material is accumulated on the receiving port side particularly at the beginning of casting, thereby further reducing the heat radiation effect. This makes it possible to slow down the cooling of the SC material during forward rotation.

  By using the SC device equipped with the cooling device of the present invention and by adopting the method of the present invention, the cooling rate of the SC material is reduced particularly in the initial high temperature region immediately after the SC material is detached from the roll. Organization control can be easily performed. Further, by a simple operation such as changing the rotating direction of the rotating body, it is possible to increase the cooling rate in the low temperature region, shorten the time for taking out the SC material, and increase the productivity. In addition, since all the cooling control is possible with one rotating body and the cooling device is small, the SC device as a whole can be downsized.

Hereinafter, the present invention will be described in detail with specific examples. First, the cooling device for SC material of the present invention will be described.
In the following drawings, the scale is not necessarily drawn accurately in order to easily explain the structure.

FIG. 1 is an external perspective view showing a state in which the cooling device 1 according to the embodiment of the present invention is taken out from the SC device, and FIG. 2 is a sectional view perpendicular to the rotation axis of the rotating body 20. As shown in these drawings, the cooling device 1 of the present invention includes a cylindrical rotating body 20 and is placed on a driving wheel 14 via a tire ring 22, and the driving wheel 14 passes through a rotating shaft 12. It is connected to a drive mechanism 10 for rotational driving.
The thickness of the SC material is usually about 0.2 mm to 0.4 mm, and is thin and brittle. Therefore, it falls into the inside of the rotary body 20 and is pulverized with the rotary stirring. However, when the cooling device of the present invention is used, it is desirable that the SC material separated from the roll is pulverized to 50 mm or less in a planar shape through a crusher. The SC material that has passed through the crusher falls into the inside of the rotating body 20 through the bonnet 26 from the receiving port 25 provided on the roll side of the rotating body through the chute.

  As shown in FIG. 2, a cooling promotion fin 30 is fixed to the inner surface of the rotating body 20, and a cover 40 is attached to cover the fin 30. When the rotating body 20 is rotated in the forward direction (clockwise in FIG. 2), the SC material loaded in the cooling device is pushed away by the cover 40 and does not contact the fin 30 or the inner surface of the rotating body 20. On the other hand, when the rotating body 20 is rotated in the reverse direction (counterclockwise in FIG. 2), the SC material is taken into the cover 40 and contacts the fins 30 and the inner surface of the rotating body 20. Therefore, the cooling rate is increased. The SC material taken into the inside of the cover is lifted with the rotation of the rotating body 20 and starts to spill out to the outside of the cover 40 after passing the highest point. Therefore, the SC material does not stay in the cover, but is renewed and stirred uniformly.

In manufacturing, the rotating body has an inner diameter of 600 mm or more, more preferably 800 mm or more in consideration of workability when a cooling fin or cover is attached to the inner surface.
The maximum diameter and length of the rotating body can be determined according to the amount of melt casting. Desirably, the volume ratio of the rotating body, that is, the cross-sectional area × the inner surface length, is designed so that the area ratio of the SC material to the cross-sectional area of the rotating body is 10% to 30% after the entire casting is finished. If it is less than 10%, the rotating body becomes unnecessarily large and the equipment cost rises. In addition, the heat capacity of the rotating body becomes relatively large compared to the SC material casting amount. This is because the cooling rate of the SC material when the is rotating forward is increased and it becomes difficult to perform sufficient structure control. On the other hand, if it exceeds 30%, the cooling rate when the rotating body is reversely rotated becomes slow, and therefore the cooling time becomes long and the productivity deteriorates. In addition, the weight of the SC material per unit area applied to the inner surface of the rotating body increases, and problems such as deterioration in the durability of a cover described later and a metal thin plate covering the cover are likely to occur.

  The opening diameter of the SC material receiving port 25 of the rotator 20 is made smaller than the inner diameter of the rotator 20 as shown in FIGS. 1 and 2 so that the SC material does not fall out. The opening diameter of the receiving port 25 is preferably about 1/3 to 1/2 of the inner diameter of the rotating body 20. The portion of the bonnet 26 provided with the receiving port 25 is configured to be removable from the rotating body 20 in order to facilitate the removal of the SC material and the maintenance work.

  The material of the rotating body is preferably made of steel in consideration of economy, workability, strength, and the like. For example, it is possible to select a welded structural steel material, a general structural rolled steel material, or the like that has good weldability. However, it is not limited to such a material.

  In order to rotate the rotating body 20, for example, as shown in FIG. 1, tire rings 22 are fitted at two locations in the long axis direction of the rotating body 20, and the portions just ride on a total of four wheels 14 of the drive mechanism 10. Arrange so that. The rotating body 20 is rotated by reversibly driving the wheel 14 on one side or both sides electrically.

By cooling the outside of the rotating body 20 with water, the cooling speed when rotating the rotating body in the reverse direction can be increased. In addition, the weight of the entire cooling device can be reduced. FIG. 3 is a partially broken side view showing an example of a water-cooling type cooling device. As a water cooling method, as shown in FIG. 3, a so-called water cooling jacket structure in which the outer side of the rotating body 20 is covered with a jacket 27 and a water channel 28 is formed in a gap between the rotating body 20 and the jacket 27 can be adopted. it can.
As another method, it is possible to employ a method in which a steel pipe or a copper pipe is welded or brazed to the side surface of the rotating body 20 at an appropriate interval, and water is allowed to flow through them. As shown in FIG. 3, the cooling water can be supplied and discharged by attaching a rotary joint 29 to the center of the rotating shaft on the opposite side of the rotary member 20 from the SC material inlet 25 side.

Instead of water cooling, the total weight of the rotating body and the fins is set to be not less than 5 times and less than 10 times the weight of the SC material to be cooled, so that the cooling can be performed by the increased heat capacity. There is an advantage that the structure of the rotating body is simplified because there is no need for water cooling.
Note that the weight ratio is set to 5 times or more and less than 10 times because if it is less than 5 times, the heat capacity is insufficient, particularly the cooling rate in the low temperature range becomes slow and the productivity is lowered. This is because the weight of the rotator increases as described above, and the structure such as the rotation drive unit of the rotator needs to be made robust accordingly.

  As shown in FIG. 2, the fins 30 arranged on the inner surface of the rotating body are attached along the substantially circumferential direction of the rotating body so that the SC material can easily enter and exit when rotated in the opposite direction. For example, it is desirable to install it by dividing it into eight or more stages. The length of each fin along the circumferential direction is preferably 1/36 or more and 1/12 or less of the inner surface circumferential length of the rotating body. If it is less than 1/36, the fins are shortened, the number of fins is increased, and the welding work becomes complicated. On the other hand, if it exceeds 1/12, the fin becomes long and it becomes difficult for the SC material to enter and exit during reverse rotation. Further, the length of the cover 40 in the circumferential direction is also increased, and the thermal strain is increased.

The thickness of the fin 30 is desirably 6 mm or more and 20 mm or less in consideration of thermal conductivity, workability, weldability, and the like, and the height is desirably 50 mm to 200 mm at the highest portion. The fins 30 are attached while being aligned in the direction of the rotation axis of the rotating body. The interval between the fins 30 is 20 mm to 100 mm. If the thickness is less than 20 mm, welding is difficult, and if it exceeds 100 mm, the total area of the fins is reduced and the cooling effect is weakened. More desirably, the thickness is 30 mm to 80 mm.
When welding the base of the fin to the inner surface of the rotating body in a T shape, the heat conduction from the fin to the rotating body can be promoted by welding over the entire length of both sides. Further, it is possible to eliminate the gap at the fin base and prevent the SC material, especially the powdered SC material, from entering the root and remaining.
It is desirable that the fin material is made of steel for the same reason as that for selecting the material of the rotating body.

As shown in FIG. 2, the cover 40 covering the fins 30 is welded and fixed along the rotation axis direction in front of the plurality of fins 30 whose one side is aligned and fixed in the forward rotation direction.
FIG. 4 shows a partially enlarged view (a) of a section perpendicular to the rotation axis and a partially enlarged view (b) of a section passing through the rotation axis of the rotating body in order to show a more preferred embodiment of the fin and cover.
As shown in FIG. 4 (b), the cover 40 is constituted by fixing a plurality of fins 30 as a unit, welding and fixing them to the ends of the fins 30b at both ends, and curving outwardly. desirable. FIG. 4B shows an example in which four fins are made into one unit.

  The temperature of the cover 40 rises due to the influence of the high temperature SC material. Since the cover 40 has a relatively short length in the circumferential direction and one side is released, the thermal strain in that direction is not so large. The thermal strain in the direction of the rotation axis can be reduced by dividing the unit into units as described above, shortening the length of the cover in the direction of the rotation axis, and further bending the cover outward. Further, the durability against the load of the SC material can be increased.

  As shown in FIG. 4A, the gap between the open end of the fin 30a that is not fixed by welding and the inner surface of the cover 40 is separated by about 10 mm to 30 mm so that the SC material does not enter and form a bridge. Is desirable.

As another construction method of the cover that relieves the thermal stress and increases the load resistance, as shown in the partial enlarged view of the cross section passing through the rotating shaft of the rotating body in FIG. As described above, the outer sides of the fins at both ends can be covered.
FIG. 5 shows a case where the number of fins 30 in one unit is four, when a gap is formed between the upper ends of all the fins 30 and the inside of the cover 40 (a), and the number of fins 30 in one unit. In the case of the five fins 30b in the center, in order to increase the load resistance, the case where the upper end is welded to the cover 40 and the gap is eliminated is shown (b).

  The number of fins in one unit is preferably 3 or more and 10 or less. This is because if the number is three or less, the number of covers increases and the welding work becomes complicated. On the other hand, the reason why the number is 10 or less is that when the number exceeds 10, the cover becomes longer, thermal strain increases, and load resistance also decreases. More desirably, the number is 4 or more and 8 or less.

As shown in FIG. 4 (a), the free end 40a side of the cover 40 is released, and when the rotating body 20 is rotated in the opposite direction, the SC material is taken inward, and the exposed portion of the SC material, the fins, and the inner surface of the rotating body. It is configured to promote contact with the water and accelerate cooling.
In a more preferred embodiment of the cover, as shown in FIG. 4A, the free end 40a that is released toward the inside of the rotating body of the cover 40 is bent toward the center of the rotating body.
By doing so, when the rotating body is rotating forward, the SC material can be prevented from spilling over the cover and entering the inside of the cover, while when rotating in the opposite direction, This is because the SC material can be easily taken into the cover.

Furthermore, as a desirable form, the exposed portions that are not covered with the surface of the cover and the cover of the rotating body are each covered with one or more metal thin plates 50a and 50b.
If the thickness of the metal thin plate is too thin, welding workability is deteriorated. In particular, since the metal thin plate on the surface is subjected to mechanical loads such as friction and shear accompanying the weight of the SC material and the rotation of the rotating body in addition to the heat load, if it is too thin, the durability is deteriorated. Therefore, it is desirable to set it as 1 mm or more.
On the other hand, when the thickness is increased, the heat capacity of the metal thin plate itself is increased, and accordingly, the effect of cooling the temperature of the SC material at the beginning of casting is increased.

  When covering with these metal thin plates, it is desirable to insert a cushioning material such as a wire mesh, for example, so as not to make direct contact with the cover as much as possible. Furthermore, embossing, such as unevenness | corrugation, can also be given to the metal thin plate previously. The periphery of the thin plate is fixed to the cover and the inner surface of the rotating body by welding. Furthermore, it may be fixed to the cover by spot welding, seam welding, or plug welding using a TIG welding machine or the like at appropriate intervals for reinforcement. Since such a joint has good thermal conductivity, heat insulation is partially reduced. Therefore, the total area of such joints should not be 20% or more, more preferably 15% or more, with respect to the entire area of the metal thin plate.

  As the material of the cover and the metal thin plate, austenitic stainless steel such as SUS304 and SUS310S is excellent in heat resistance, excellent workability such as bending, cutting and welding, and from the viewpoint of availability and economy. Steel, SUH304 and SUH310 series austenitic heat resistant steels are suitable. Furthermore, a nickel-base alloy or the like excellent in high temperature strength can be employed.

As another embodiment of the cover, instead of covering with a thin plate, a ceramic film such as alumina can be formed by a method such as plasma spraying. When covering with a plasma film, blasting is performed in advance to roughen the surface and increase the adhesion strength of the film.
Furthermore, a plasma sprayed coating can be formed and covered with one or more metal thin plates. In that case, it is desirable to apply a glass tape or the like in advance on the portion where the metal thin plate is welded to the cover or the inner surface of the rotating body so that the sprayed coating is not formed.

In another embodiment of the cooling device, the angle formed by the rotation axis of the rotating body and the horizontal plane is variable.
For example, as shown in FIG. 6, the entire cooling device 3 including the rotation drive mechanism is mounted on the tilt table 17, and the angle is adjusted using an electric or hydraulic cylinder 18 or the like. The tilting fulcrum 19 is placed in the vicinity of the lower part thereof so that the position of the SC material receiving port 25 does not move as much as possible.

  In particular, cooling can be slowed by changing the angle formed by the rotation axis with the horizontal plane at the beginning of casting and bringing the SC materials closer to the receiving port. By changing the angle in this way, the cooling rate can be controlled. Further, after the cooling is completed, the SC body can be easily taken out by pulling out the rotating body together with the tilting table from the chamber and rotating the receiving port side downward, thereby improving workability.

Furthermore, in another embodiment of the cooling device, an electric heater is disposed at the position of the central axis of the rotating body. FIG. 7 shows a cross-sectional view of the cooling device 4 passing through the rotation axis as viewed from the side. As shown in the figure, the electric heater 60 may be arranged with one side fixed in the vicinity of the center of the wall opposite to the SC material receiving port 25 side of the rotating body.
Energization can be performed through a slip ring (not shown) attached to the rotating shaft when a rotary joint for water cooling is provided around the rotating body main body. The purpose of heating is to reduce the temperature difference between the SC material and the inside of the cooling device by keeping the inside of the cooling device as high as possible in order to make the cooling rate of the SC material at the beginning of casting as slow as possible. It is desirable that the temperature inside the cooling device be as high as possible to be about 300 ° C. or higher and about 600 ° C.
The power supply can be determined in accordance with the degree of structure control of the target SC material, and is set larger when it is desired to cool down the high temperature region more slowly. It is desirable to determine within a range of 3 to 30 kW per 100 kg of melt casting.
By energizing and heating before the start of casting and preheating the inner surface of the rotating body, the cooling rate of the SC material, particularly immediately after the start of casting, can be reduced.

The present invention includes an SC device provided with such a cooling device.
By using the SC device provided with the cooling device described above, it is possible to reduce the cooling rate of the SC material during or after casting and to control the distribution state of the R-rich phase. . In addition, the cooling speed can be increased and productivity can be increased by a simple operation such as changing the rotation direction of the rotating body of the cooling device. Since the cooling speed can be changed with one rotating body, the capacity of the cooling device is small, and therefore the entire SC device can be miniaturized.

  Moreover, in the SC material immediately after separation from the roll, since the R-rich phase is in a molten state, in the case of a stationary type cooling device, the SC materials are fused together to form a large mass, and are handled in a later process including the removal operation. Becomes difficult. In particular, as the cooling rate in the high temperature range is decreased, such a tendency becomes stronger and the workability is remarkably impaired. In the apparatus of the present invention, since the rotating body is always rotated and the SC material is stirred, such a fusion phenomenon does not occur. Further, since the agitation is performed, there is an advantage that the thermal history of the individual SC material flakes is made uniform and the uniformity of the structure is increased.

Below, embodiment of the cooling method using the cooling device of this invention is described.
In the present invention, as a method for cooling the SC material, using the SC device provided with the cooling device described above, the casting of the rotating body is started in the normal rotation state, and after the predetermined time has elapsed after the casting is finished, the rotating direction of the rotating body is changed. The cooling rate is controlled by rotating in the reverse direction.

In the normal rotation state of the rotating body, the SC material does not directly touch the fins or the inner surface of the rotating body, so the cooling rate is slow and the SC material is longer in a high temperature range of about 800 ° C. to 600 ° C., where the structure change easily proceeds. Can keep time. After a predetermined time has elapsed after the casting is finished, the rotation direction of the rotating body is switched and rotated in the reverse direction, whereby the SC material is taken into the inside of the cover, and directly touches the fins and the inner exposed portions of the rotating body, and is rapidly cooled. .
Thus, the cooling rate can be changed by a simple operation such as changing the rotation direction of the rotating body of the cooling device. Furthermore, by changing the timing for switching the rotation direction of the rotating body, the distribution state of the R-rich phase is changed, and the desired structure can be easily built.

  The timing for changing the rotation direction is desirably selected within the range of 1 minute to 1 hour after the end of casting, with the SC material cooling temperature range of 800 ° C. to 600 ° C. as a target. This is because, within 1 minute, the SC casting material in the latter stage of casting has a short time for passing through the high temperature region, the R-rich phase does not sufficiently reach thermal equilibrium, and the average interval between the R-rich phases becomes too narrow. On the other hand, since the average temperature of the entire SC material is already below the melting point of the R-rich phase and the structural change is less likely to occur after 1 hour or longer. Therefore, the cooling station time is simply prolonged. More desirably, it is 2 minutes or more and less than 30 minutes.

Since the R ₂ T ₁₄ B-based alloy contains about 30 wt% of an active rare earth element, it easily oxidizes when exposed to the atmosphere at a high temperature, and the oxygen concentration increases. In general, oxidation is remarkable at 200 ° C. or higher, and it is necessary to cool it to 150 ° C. or lower and take it out. In particular, when a water-cooled rotating body is used, the SC material is rapidly cooled when the rotating direction of the rotating body is changed, coupled with the effect of increasing the heat transfer area by the fins, and is cooled to 150 ° C. or less in a short time. It becomes possible.

  The rotational speed of the rotating body is set so that the centrifugal force does not exceed 0.5 G on the inner surface of the rotating body. If the speed is too fast, the load on the cover and the metal thin plate covering the cover will increase, and the durability will deteriorate. On the other hand, if it is too slow, the stirring effect is weakened, and there is a possibility that the SC material flakes are fused together. Desirably, it is about 0.1G-0.3G.

  Another cooling method of the present invention is a cooling method using an SC device provided with a cooling device in which an angle formed by a rotating shaft of a rotating body and a horizontal plane is variable. Casting is started so that the receiving shaft side is lower than the horizontal plane, and after a predetermined time has passed, the rotating shaft is adjusted to be horizontal or the receiving side is raised. Switch direction and rotate in the opposite direction.

  By starting casting so that the receiving shaft side is lower than the horizontal plane, the SC material can be stored on the receiving port side, and the heat radiation effect can be reduced. In particular, at the beginning of casting, the temperature of the rotating body and the cover is low, and the temperature of the SC material is likely to decrease. In particular, when the spread of the SC material is fast, such a tendency is further increased. By adopting such a cooling method, it is possible to prevent the SC material from cooling at the beginning of casting from being accelerated.

  The angle between the rotation axis of the rotating body at the start of casting and the horizontal plane and the time for changing it can be determined by looking at the results of actual use so that the SC material does not spill from the receiving port. Moreover, it is not necessary to make it constant during casting, and can be changed as appropriate.

Another cooling method of the present invention uses an SC device equipped with a cooling device provided with an electric heater, energizes the electric heater, stops the energization immediately before the start of casting in a rotating state of the rotating body, and further ends the casting. After the predetermined time has elapsed, the rotation direction of the rotating body is switched and rotated in the reverse direction.
By energizing the electric heater before the start of casting and preheating the inner surface of the rotating body to 300 ° C. to 600 ° C., the cooling rate of the SC material, particularly at the beginning of casting, can be further reduced.

  Heating by the heater is started at least 10 minutes before the start of casting in order to enhance the preheating effect. On the other hand, if it is too long, it reaches a steady state and wastes power, so it is desirable that it be within one hour.

  Even if a heater is arranged on the inner side and preheating is performed, only the thin metal plate is substantially heated when the cover or the cooling device covered with the thin metal plate is used. In the latter case, the temperature rise of the cover, whose contribution cannot be ignored in terms of heat capacity, is also suppressed. Therefore, the inner surface of the rotating body can be preheated efficiently even with a relatively low output heater. In addition, the cooling rate of the SC material when rotating the rotating body in the reverse direction can be sufficiently increased without being affected by the preheating, and the cooling time can be shortened.

Yet another cooling method is a cooling method using an SC device in which an angle formed by a rotating shaft of a rotating body and a horizontal plane is variable in a cooling device provided with an electric heater. After energizing the electric heater, stop the energization just before the start of casting, start casting with the rotating body in the normal rotation direction and the rotating shaft lower than the horizontal plane on the receiving side, and after a predetermined time has passed, rotate the rotating shaft horizontally Or it adjusts so that a receiving side may become high, and also after the predetermined time progress after completion | finish of casting, the rotation direction of a rotary body is switched and it rotates in a reverse direction.
In addition to the preheating effect by the electric heater, starting the casting so that the receiving shaft side is lower than the horizontal plane, the SC material can be stored on the receiving side, and the heat dissipation effect can be further reduced. Cooling during normal rotation can be delayed.

  Hereinafter, the cooling device, the SC device, and the cooling method of the present invention will be described in more detail with reference to examples.

  The rotating body used as the cooling device had a thickness of 40 mm, an inner diameter of 700 mm, and a length of 800 mm, and was produced using a rolled steel material for welded structure. Furthermore, fins having a rough dimension of 60 mm × length 120 mm cut out using a steel plate having a thickness of 12 mm are divided into 12 equal parts in the circumferential direction, and arranged in 13 rows at a pitch of 52 mm in the rotation axis direction. Welded and fixed to the inner surface. Further, a cover made of a stainless steel plate made of SUS310S having a thickness of 4 mm was covered in the same manner as in FIG. 4 with four fins as one unit and a curved surface formed on the outside. The total weight of the rotating body and the fins was about 650 kg.

The cover was further covered with a thin plate made of SUS310S having a thickness of 1.5 mm, and the periphery was fixed by welding. Similarly, the inner surface of the bonnet of the SC material receiving port and the inner surface of the end plate portion on the opposite side of the receiving port of the rotating body are also covered with a thin metal plate, and directly connected to the SC material, the rotating body main body, and other parts having a large heat capacity. I tried not to touch it.
Such a cooling device was installed in an SC device equipped with a 100 kg vacuum high frequency induction melting furnace as schematically shown in FIG.

  The dissolution weight is 80 kg, metal neodymium, electrolytic iron, and ferroboron are blended so that the blending composition is 31.5 wt% and boron is 1.0 wt%. In a normal melting method, in an atmosphere of 250 Torr of argon Dissolved. After melting, the casting was cast at a casting width of 200 mm and a water-cooled roll peripheral speed of 1.2 m / s with the rotating body rotated forward.

After 10 minutes from the end of casting, the rotation was stopped and further rotated in the reverse direction.
Further, after 2 hours, the rotation was stopped and the chamber was opened, and a measurement terminal of a sheath thermocouple was inserted into the SC material, and the temperature was measured. As a result, even the portion showing the maximum temperature was sufficiently low at 130 ° C. or lower, and no discoloration due to oxidation occurred.

The average thickness of the SC material was 0.31 mm. The surface of the SC material was embedded in a resin so that a cross section in a direction perpendicular to the surface of the SC material could be observed, polished, and the structure was observed with a reflected electron beam image using a scanning electron microscope. Using the structure photograph thus obtained, the distance between the R-rich phases was measured by the line segment method at 10 cross-sections and approximately the center in the thickness direction of the SC material. As a result, the interval between the R-rich phases was 6.3 μm, and the secondary lamellar R-rich phase almost disappeared, indicating a structure in the case where the cooling rate in the high temperature range is sufficiently slow. It was judged to be the optimum structure as a raw material alloy for a system magnet.
In addition, the SC material could be easily taken out by pulling out the cooling device from the SC device and tilting it forward so that the receiving side is lowered.

A cooling device having a water cooling jacket structure with the same internal dimensions of the rotating body as in Example 1 was prepared. The structure and dimensions of the fins and cover were made the same as in Example 1. However, the rotating body was manufactured using a steel plate having a thickness of 20 mm and a jacket having a thickness of 8 mm.
Such a cooling apparatus was installed in the SC apparatus provided with the same 100 kg vacuum high frequency induction melting furnace as Example 1.

  The dissolution weight is 100 kg, and in the blending composition, neodymium is 27.0 wt%, dysprosium is 5 wt%, boron is 1.0 wt%, and neodymium metal, metal dysprosium, electrolytic iron, ferroboron are blended, It melt | dissolved in the atmosphere of argon 250 Torr by the normal melt | dissolution method. After melting, the casting was cast at a casting width of 200 mm and a water-cooled roll peripheral speed of 1.0 m / s with the rotating body rotated forward.

After 2 minutes from the end of casting, the rotation was stopped and further rotated in the reverse direction.
Further, after 1.5 hours, the rotation was stopped and the chamber was opened, and a measurement terminal of a sheath thermocouple was inserted into the SC material, and the temperature was measured. As a result, even the portion showing the maximum temperature was sufficiently low at 80 ° C. or lower, and no discoloration due to oxidation occurred.

  The average thickness of the SC material was 0.28 mm. In the same manner as in Example 1, the cross-sectional structure of the SC material was observed. As a result, the interval between the R-rich phases was 4.2 μm, indicating a structure considered to be optimal as an alloy raw material for manufacturing a high coercive force type magnet.

(Comparative Example 1)
Using the same SC apparatus as in Example 1, an alloy having the same composition as in Example 1 was melt-cast under the same conditions for the amount of dissolution, and the internal dimensions of the SC material of width 320 mm x length 950 mm x height 600 mm were stored. Collected in a container.
The storage container in which such a cooling device was set was installed in an SC device 51 equipped with a 100 kg vacuum high frequency induction melting furnace as shown in FIG.
After the completion of casting, 24 hours later, the chamber was opened, and a measuring terminal of a sheath thermocouple was inserted into the SC material, and the temperature was measured. As a result, a portion showing a temperature of 250 ° C. or more remained, and when transferred from the storage container to the drum, the SC material was oxidized and a considerable portion was discolored.

  The average thickness of the SC material was 0.30 mm. In the same manner as in Example 1, the cross-sectional structure of the SC material was observed. As a result, the R-rich phase interval was 7.3 μm, indicating a wider R-rich phase interval than that in Example 1. Organizationally, it was thought that it was a structure that could be used as a raw material for highly magnetized magnets. However, in order to prevent oxidation, it was necessary to hold in the chamber for 24 hours or more, and it was judged that productivity was poor and it could not be adopted as mass production equipment.

(Comparative Example 2)
In the same SC material storage container as that in Comparative Example 1, a cooling device was prepared in which rectangular water cooling boxes having a width of 50 × length of 780 × height of 600 mm were set at intervals of 3 rows and 50 mm.
Then, using the same SC apparatus as in Example 1, an alloy having the same composition as in Example 1 was melt cast. The dissolution weight was 80 kg as in Example 1. After 24 hours from the end of casting, the chamber was opened and the SC material was taken out.
The average thickness of the SC material was 0.31 mm. In the same manner as in Example 1, the cross-sectional structure of the SC material was observed. As a result, the portion of the R-rich phase was found to be 3 μm or more, but many portions of less than 3 μm were also found. Generally, the R-rich phase was narrow and varied widely, and it was used as a raw material for neodymium-based magnet alloys. Indicated an unsuitable organization.

  A cooling device having a water-cooled jacket structure provided with fins and covers having the same internal dimensions and the same structural dimensions as those of Example 2 was prepared. The cooling device is further provided with a 5 kW electric heater as shown in FIG. 7 in the vicinity of the central axis of the rotating body, and the entire rotating body is placed on a tilting mechanism as shown in FIG. It was configured to be controllable.

  The dissolution weight was 100 kg, and dissolution was performed in the same composition as in Example 1. The electric heater was energized about 30 minutes before the scheduled casting start time, the inner surface of the rotating body was preheated, and energization was stopped immediately before the start of casting. Casting was started at a casting width: 200 mm and a water-cooled roll peripheral speed: 1.2 m / s with the rotating body rotated forward and tilted by 5 degrees with respect to the horizontal plane so that the inlet side was lowered. After 1 minute from the beginning of casting, the inclination of the rotating shaft was changed so that the receiving side was 3 degrees higher than the horizontal plane. Further, after 10 minutes from the end of casting, the rotation was stopped and further rotated in the reverse direction.

  Further, after 1.5 hours, the rotation was stopped and the chamber was opened, and a measurement terminal of a sheath thermocouple was inserted into the SC material, and the temperature was measured. As a result, even the portion showing the maximum temperature was sufficiently low at 90 ° C. or lower, and no discoloration due to oxidation occurred.

  The average thickness of the SC material was 0.30 mm. In the same manner as in Example 1, the cross-sectional structure of the SC material was observed. As a result, the interval between the R-rich phases was 6.4 μm, indicating a structure considered to be optimal as an alloy raw material for producing a highly magnetized magnet.

Since the present invention is configured as described above, it has the following effects.
That is, the cooling device of the present invention can increase the cooling rate in the high temperature range, which has a great influence on the structure control, and increase the cooling rate in the low temperature range, which affects the productivity. In particular, in an SC device for manufacturing a raw material alloy for a neodymium-based magnet, when an SC material separated from a water-cooled roll is incorporated and used as an apparatus for cooling, an alloy having an optimum structure according to the use of the magnet can be manufactured. It can be a device. And since cooling time can also be shortened, productivity can be improved.

Furthermore, the cooling rate can be changed by switching the rotation direction with a single rotating body, and a compact apparatus can be obtained.
Therefore, industrial applicability is sufficiently high.

  It is an external appearance perspective view of the cooling device of the present invention.   It is sectional drawing of a perpendicular direction to the rotating shaft of the cooling device of this invention.   It is a partially broken side view of the jacket water cooling type cooling device of the present invention.   It is a fragmentary sectional view showing one embodiment of the fin and cover of the present invention.   It is a fragmentary sectional view showing other embodiments of the fin and cover of the present invention.   It is a figure which shows the mechanism for making the angle of the cooling device of this invention variable.   It is sectional drawing which shows the attachment condition of the heater of the cooling device provided with the heater of this invention.   It is a figure explaining schematic structure of the strip casting apparatus of this invention.   It is a figure explaining schematic structure of the conventional strip casting apparatus.

Explanation of symbols

1, 2, 3, 4 Cooling device 9 SC material 10 Drive mechanism 14 Drive wheel 16 Inclination mechanism 20 Rotating body 22 Tailing 25 Receptor 26 Bonnet 29 Rotary joint 30 Fin 40 Cover 50a, 50b Metal thin plate 60 Heater 70 Melting chamber 71 Casting chamber 72 Crucible 73 Water-cooled roll 76 Crusher 77 Shout

Claims (19)

  An apparatus for receiving and cooling flake-like cast flakes after being detached from a roll in a strip casting apparatus for an alloy for neodymium-based sintered magnets, which is cylindrical and has a rotating body whose direction of rotation is variable between forward and reverse. A plurality of fins are provided inside and a cover is provided so as to cover the fins. When the rotating body is rotated in the forward direction, the cast flakes are pushed away so that the cast flakes do not contact the inner surfaces of the fins and the rotating body. On the other hand, when the rotating body is rotated in the reverse direction, an opening is provided on the front surface on the reverse rotation side so that the cast flake is taken in and the cast thin piece contacts the fin and the inner surface of the rotating body. A cooling device characterized by being configured as described above.   The cooling device according to claim 1, wherein the outside of the rotating body is water-cooled.   The cooling device according to claim 1, wherein the total weight of the rotating body and the fins is set to be not less than 5 times and less than 10 times the weight of the cast flake to be cooled.   The fin is made of a metal plate, is maintained at a distance of 20 mm to 100 mm over almost the entire length in the major axis direction of the rotating body, and is fixedly arranged by welding or brazing along the circumference of the rotating body, and along the rotating direction of the rotating body. The cooling device according to claim 1, wherein the cooling device is arranged over a plurality of stages.   The cover is made of a metal plate, one end along the longitudinal direction of the rotating body of the metal plate is welded and fixed to the inner surface of the rotating body, and the other end of the metal plate is released toward the inside of the rotating body. It is comprised, The cooling device of any one of Claims 1-4 characterized by the above-mentioned.   The cooling device according to claim 5, wherein an end of the cover that is released toward the inside of the rotating body is bent toward the center of the rotating body.   The cover is composed of 3 to 10 fins as a unit, welded and fixed to the ends of the fins at both ends, and curved outwardly in a sectional view along the longitudinal direction of the rotating body. The cooling device according to claim 5, wherein the cooling device is provided.   7. The cover according to claim 5, wherein the cover is configured so as to cover the outside of the fins at both ends thereof with 3 to 10 fins as one unit. The cooling device described.   The cooling device according to any one of claims 1 to 8, wherein a width of a gap between the fin release end and the cover inner surface is 10 mm to 30 mm.   The cooling device according to any one of claims 1 to 9, wherein a part of the outer surface of the cover and an inner surface of the rotating body that is not covered with a cover is covered with one or more metal thin plates.   The cooling device according to any one of claims 1 to 9, wherein a portion of the outer side of the cover and an inner surface of the rotating body that is not covered with a cover is thermally sprayed with ceramics.   10. The structure according to claim 1, wherein the outer part of the cover and the inner surface of the rotating body not covered by the cover are sprayed with ceramics and further covered with one or more metal thin plates. The cooling device according to any one of claims.   The cooling device according to any one of claims 1 to 12, wherein an angle formed by a rotating shaft of the rotating body and a horizontal plane is made variable.   The cooling device according to any one of claims 1 to 13, wherein an electric heater is disposed at a position of a central axis of the rotating body.   A strip cast apparatus for an alloy for neodymium-based sintered magnets, comprising the cooling apparatus according to claim 1.   Using the strip cast apparatus provided with the cooling device according to any one of claims 1 to 12, casting is started in a state where the rotating body is rotated in a normal rotation state, and after a predetermined time has elapsed after the end of casting, the rotating body is rotated. A method of cooling an alloy cast flake for neodymium-based sintered magnet, wherein the direction is switched and the direction is rotated in the reverse direction.   Casting is started by using the strip casting apparatus provided with the cooling device according to claim 13 so that the receiving shaft side is lower than the horizontal plane, and after a predetermined time, the inclination of the rotating shaft is set to be horizontal or receiving port. A method for cooling an alloy cast flake for a neodymium-based sintered magnet, characterized in that the side is made higher than a horizontal plane, and further, after a predetermined time has elapsed after the end of casting, the side is rotated in the reverse direction.   Using a strip cast device comprising the cooling device according to claim 14, the electric heater is energized, the energization of the rotating body is stopped immediately before the start of casting, and the rotation is continued after a predetermined time has elapsed after the end of casting. A method for cooling an alloy cast flake for a neodymium-based sintered magnet, wherein the body rotation direction is switched and the body is rotated in the opposite direction.   After energizing the electric heater using the strip cast device provided with the cooling device according to claim 14, the energization is stopped immediately before the start of casting, the rotating body is in the normal rotation direction, and the rotating shaft is positioned on the receiving port side from the horizontal plane. Casting is started in such a way that, after a predetermined time elapses, the inclination of the rotation shaft is set to be horizontal or the receiving port side is higher than the horizontal plane, and further, after a predetermined time elapses after the casting is finished, it is rotated in the reverse direction. A cooling method for alloy cast flakes for neodymium sintered magnets.

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