JP2614004B2 - Method and apparatus for dissolving and injecting active metal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the precision casting of active metals such as titanium and zirconium, and particularly to the production of small precision castings such as dental, orthopedic or industrial precision parts, in a small amount and contaminated. The present invention relates to a method and an apparatus for dissolving / injecting an active metal, in which a hot active metal melt having no air is dropped vertically from a crucible without touching other objects during the fall and directly injected into the center of a mold gate.

[0002]

2. Description of the Related Art Titanium and titanium alloys have recently attracted particular attention as orthopedic artificial bones and dental prostheses because of their excellent heat and corrosion resistance, high specific strength, and extremely excellent biocompatibility. It was started. However, on the other hand, titanium has a very high chemical affinity for oxygen, nitrogen, carbon, etc., and especially at high temperatures, it immediately reacts with almost all refractories containing these elements to decompose it,
They are strongly bonded to these elements and become contaminated, which tends to reduce their mechanical properties. Moreover, since the melting points of reaction products with these elements, for example, titanium oxide, titanium nitride, and titanium carbide are all much higher than the melting point of titanium itself, these reaction products are once generated. In many cases, the fluidity was significantly impaired, and in cases of severe contamination, casting was often difficult.

[0003] Therefore, it is difficult to dissolve an active metal such as titanium by a refractory crucible used for dissolving a low-active metal such as iron or copper, and the reactivity with the active metal is extremely low. Even in the case of induction melting with a refractory crucible such as calcia (CaO) or yttria (Y ₂ O ₃ ), as long as it does not completely cut off the contact between the residual liquid of the molten metal and the air for the first time, each time it is repeated, Pollution will progress. When melting is performed on these refractory crucibles using an arc, CaO decomposed by the high-temperature arc is used.
Alternatively, the active metal tends to be contaminated by oxygen in Y ₂ O ₃ . For this reason, it can be said that it has been practically almost impossible to obtain a stable active metal melt without any contamination by melting the refractory crucible.

Conventionally, in dissolving an active metal such as titanium, a method for avoiding contamination due to a reaction with a crucible and obtaining a clean active metal melt has been most widely used industrially as shown in FIG. This is a skull dissolution method using a water-cooled copper crucible 34. In this case, the melting is performed in a vacuum or an inert gas atmosphere such as argon, and the metal consumable electrode 33 is melted.
The active metal melt 36 melted by the direct current arc 35 generated between the molten metal and the molten material in the water-cooled copper crucible 34 is cooled by the water-cooled copper crucible 34 to form a solidified shell or skull 36S on the inner surface thereof and melted. The body 36 is stored in a skull 36S of exactly the same composition, and when the melt 36 reaches a desired temperature and amount, the horizontal rotating shaft 37 is rotated to be poured into the mold.

Recently, Japanese Patent Publication No. 3-44133 discloses a method in which the above-mentioned skull melting is further advanced, and a cylindrical crucible is constituted by a plurality of vertically divided water-cooled metal crucibles, and an active metal is induced and melted. It has been disclosed. Furthermore, as a structure in which the bottom wall of a cylindrical crucible composed of a plurality of vertically divided water-cooled metal crucibles is separated, induction melting is performed, and the bottom wall is separated from the cylindrical side wall by a driving mechanism. Japanese Patent Laid-Open No. 4-138865 proposes a method in which the molten metal is dropped vertically downward and poured into a mold.

Next, conventionally, in precision casting such as dental casting in which a relatively small amount of metal is melted, means for melting an active metal such as a titanium alloy include a tungsten arc or TIG arc in an atmosphere of an inert gas such as argon, and a non-metal alloy. Water-cooled crucibles have been used most often. A typical example is a method in which a molten material (ingot) is placed on a crucible having a circular opening in the center, and the active metal melted by the TIG arc is allowed to fall naturally through the opening and injected into a mold. (See Japanese Patent Publication No. 58-5749), or a device in which a crucible is divided into two and opened in both sides to perform injection optionally, or a device in which a horizontal axis of a box-shaped crucible is rotated to perform injection (Japanese Unexamined Patent Publication No. Hei. Japanese Patent Laid-Open No. 3-19353), or a device that tilts around a horizontal axis eccentric to one of the crucibles (see Japanese Patent Application Laid-Open No. 3-193260) has been proposed.

[0007]

However, the skull melting method using a DC arc widely used in an industrial furnace as shown in FIG. 14 and the above-mentioned Japanese Patent Publication No. 3-44133.
And the skull melting method by induction heating disclosed in JP-A-4-138865 are common in that the skull melting of the active metal is performed in a water-cooled metal crucible having side walls, and the melt is Since it is cooled not only from the bottom surface but also from the side surface, heat loss is large, and it is considered that overheating of the molten material is considerably difficult even in an industrial furnace having a considerably large capacity. Therefore, the induction heating by the water-cooled metal crucible as described above can be used for small precision casting such as dental casting of active metal that requires a heating of at least about 100 ° C. in order to fill a very thin tip portion having a small amount of melting. The skull dissolution method was not applied.

[0008] Among the above-mentioned methods of injecting a small amount of active metal used for dental casting and the like, the method of a natural fall method through an opening of a non-water-cooled metal crucible injects a molten material into the center of a mold gate. Although there is an advantage in that the active metal melt passes through the opening of the low temperature metal crucible, a considerable amount of heat is lost due to heat conduction, and it is regrettable to obtain a high temperature melt. Also, if the diameter of the metal crucible is too small, the passage of the molten material becomes difficult, and if the heating is forcibly performed, the melting of the crucible is likely to occur.On the other hand, if the diameter of the metal crucible is large, the passage of the melt becomes easy, but the unmelted portion However, there is a problem that the temperature of the molten material is lowered by dropping together, and a sufficient hot-water effect cannot be obtained, resulting in poor running.

Next, the conventional method of rotating or tilting the metal crucible has the advantage that the injection can be performed at will, but when the amount of the active metal melt is small, the temperature due to the contact with the crucible during the casting is reduced. Since the melt easily falls and it is difficult to inject the melt into the center of the mold gate accurately, the melt that has fallen off the center of the gate is unevenly distributed, and a sufficient feeder effect cannot be obtained.
For this reason, there were many cases where it was difficult to obtain a sound casting.

In addition, in the case of dental casting in which a small amount of active metal is melted and injected, the non-water-cooled metal crucible has its own heat capacity. It was easy to cause melting damage and it was difficult to reach a sufficient superheating temperature, and there was no difference between the oral method and the injection method.

Furthermore, in the dental casting of active metals such as titanium, the TIG arc, which has been most frequently used as a heat source for melting, has a low energy density, a flat arc shape, and a low heat transfer efficiency. It was difficult to heat to temperature. For this reason, the adoption of a skull melting method using a water-cooled metal crucible that is most suitable for dissolving this type of active metal has been prevented, and many of them have been forced to dissolve using a non-water-cooled metal crucible.

[0012] Therefore, an object of the present invention is to solve the above-mentioned problems in a precision casting method using a relatively small amount of active metal, and to inject a clean and high-temperature melt free from contamination at the center of a mold gate. And a device therefor.

[0013]

In order to achieve the above object, the present invention first uses a shallow dish-shaped metal crucible for melting a skull only by cooling the bottom without side cooling. As a result of the trial experiment, it was found that skull dissolution capable of leaving a flat spherical melt and a disk-shaped skull at the bottom was possible. Next, regarding the method of injecting the melt, the speed of the free-falling object is 0 at the start of the fall,
Paying attention to increasing with time thereafter, prior to the molten material falling vertically, the molten metal is rotated from its position to another position by rapidly rotating a dish-shaped metal crucible downward by about 90 ° about one end thereof. It is made possible to drop vertically without touching the object and directly inject it into the center of the mold gate.

The apparatus for achieving the method of melting and pouring the active metal comprises a melting means and a rotating means of a crucible. The melting means comprises an arc generator and a metal crucible. In the form of a shallow dish having an upper surface consisting of an inclined surface surrounding a circular horizontal surface, the rotating means of the metal crucible rotates the crucible downward rapidly around one end thereof to precede the vertical drop of the melt. And has the function of retracting the molten material out of the fall trajectory.

The upper surface of the metal crucible has a shallow dish shape composed of a circular horizontal surface for holding a molten material (ingot) at the center and achieving skull melting only by cooling the bottom surface, and an inclined surface surrounding the circular horizontal surface. The inclined surface must prevent the melt from moving in the lateral direction, and must not touch the side surface of the melt. For this purpose, assuming that the angle of the inclined surface with respect to the circular horizontal plane is α, the contact angle of the metal melt on the skull is β, and the weight of the active metal to be dissolved is Wgr, the values of D and α are 0.45 W ^{By making the range of 1/2} ≦ D ≦ 0.6W ^1/2 10 ° ≦ α <180 ° −β, a flat spherical melt held on a disk-shaped skull can be obtained. I was able to find out.

By using the above-described method and apparatus for dissolving and pouring an active metal, a clean flat spherical metal melt free of contamination is directly injected into the center of a mold gate without any contact with other objects. It became possible. However, as described above, the energy density of the TIG arc is low, and the non-water-cooled metal crucible has its own heat capacity limit. Was not always enough. Therefore, in order to dissolve and inject a small amount of active metal and completely fill the thin portion at the tip, at least 100 °
In the case of dental casting requiring near C overheating, overheating of the metal melt is important, and a higher temperature heat of melting heat may be desirable.

[0017] For this reason, first, the aim was to apply a melting heat source having a higher energy density than the TIG arc.
Although the energy density of the TIG arc is only in the order of 10 ⁴ W / cm ² , the energy density is more than two orders of magnitude higher than this.
0 ⁶ as belonging to W / cm ² or more so-called high-energy density dissolution heat source with a value, plasma arc,
There are an electron beam and a laser beam. Among them, in consideration of economy, workability and energy concentration characteristics, a plasma arc most suitable for the purpose of melting a small amount of active metal is adopted. In addition, the TIG arc melting requires an inert gas pressure higher than the normal pressure.
The arc melting can be performed in an atmosphere of an inert gas at a low pressure or higher, as well as at a normal pressure or higher. This proved that in a melting experiment ranging from normal pressure or higher to several torr, it was possible to obtain a high-temperature molten metal which was completely free of contamination and was sufficiently heated compared to the TIG arc.

By employing the above-mentioned plasma arc, it has become possible to carry out regular skull melting using a water-cooled metal crucible instead of the conventional non-water-cooled metal crucible. In the present invention, as a result of a trial experiment using a water-cooled metal crucible provided with a cooling water passage inside the above-mentioned shallow dish-shaped metal crucible, a high-temperature flat spherical metal melt at the top and a thin disk-shaped bottom It was found that complete skull dissolution leaving the skull was achieved. As a result, it is possible to dissolve the skull in a complete form even in a small amount of active metal of about 50 gr or less, and to obtain a sufficiently heated active metal melt free of contamination.

Next, in this metal melting / injecting apparatus, the rotating means for rotating the dish-shaped metal crucible penetrates into the wall of the melting chamber from both sides outside the melting chamber and has a pair of cooling water passages inside. A rotating shaft of a metal crucible also having a cooling water passage therein is fixed to the horizontal rotating shaft, and the horizontal rotating shaft is rotated by a driving device provided outside the melting chamber, whereby the metal crucible is substantially 90 °. It is designed to rotate downward.

With respect to the rotating means of the metal crucible by the driving device outside the melting chamber, the present invention further conducted various studies aiming at limiting the rotating portion only to the inside of the melting chamber, and as a result, as a rotating means of the metal crucible. And found a method of utilizing the driving force of the torsion coil spring. Specifically, the rotating means for rotating the dish-shaped metal crucible is provided at the tip of a pair of horizontal metal pipes that penetrate and are fixed to the wall of the melting chamber from both sides outside the melting chamber and flow cooling water inside. A bearing portion is provided, and a rotating shaft of a metal crucible through which cooling water flows is rotatably mounted in the bearing portion, and the metal crucible is substantially rotated by a symmetric torsion coil spring locked to the rotating shaft. It is designed to be rotated downward.

[0021]

FIG. 5 shows a plasma arc 5 according to the present invention.
FIG. 4 is an explanatory diagram showing the principle of skull dissolution of active metal by a water-cooled metal crucible 4. It has been known that when a large drop of mercury is placed on a horizontal glass plate, it becomes a flat sphere of a certain thickness. 5, it was confirmed by preliminary experiments that a flat spherical melt having a constant thickness h was similarly obtained as shown in FIG. However, in the case of mercury, it is on a glass plate, but in this case, it is different in that it is dissolved on a skull 6S of the same metal. Therefore, if the weight of the molten material increases, the melt spreads only in the lateral direction while keeping the flat spherical shape.
The appropriate diameter D of the circular horizontal plane 42 of the horizontal plane can be determined experimentally. Next, the upper surface of the metal crucible 4 is composed of a circular horizontal surface 42 for mounting the molten material and holding the melt 6 and an inclined surface 43 surrounding the circular horizontal surface 42. Now, assuming that the diameter of the circular horizontal surface 42 is Dcm, the angle of the inclined surface 43 of the crucible 43 with respect to the circular horizontal surface 42 is α, the contact angle of the melt 6 on the skull 6S is β, and the weight of the melting metal material is Wgr. It was found that the range of 45W ^1/2 ≦ D ≦ 0.6W ^1/2 10 ° ≦ α <180 ° −β was appropriate. The lower limit of the inclination angle α of the inclined surface 43 with respect to the circular horizontal surface 42 is set to 10 ° in order to prevent the active metal melt 6 from fluctuating in the horizontal direction due to arc blowing. By making the upper surface of the water-cooled metal crucible 4 into the above-described shape, the melt 6 is prevented from moving in the lateral direction and is held at the center of the metal crucible 4, and there is no possibility that the side surface of the melt 6 touches the metal crucible 4. In addition, skull dissolution is achieved only by bottom cooling.

Injection is performed by rapidly rotating the metal crucible 4 downward around the rotating shaft 41 at one end thereof, so that the melt 6
The melt 6 is retracted out of the fall trajectory of the melt 6 in advance of the above, so that the melt 6 is dropped vertically from the position directly onto the center of the mold gate without touching any other object. FIGS. 10 and 11 are schematic diagrams in which the relative positions of the free-falling melt 6 and the metal crucible 4 after the start of the injection are analyzed with time. The diameter of the metal crucible 4 is 40 mm, and the rotation from the center of the metal crucible 4 is shown. The distance to the center O of the shaft 41 is 30 mm, and the metal crucible 4 moves around the center O of the rotating shaft 41 as shown in FIG.
0 indicates a rotation speed of 20 rad / s, and FIG. 11 shows a phenomenon at a time of rotation at a constant angular speed of 16 rad / s. In this case, about 90
時間 The time required for rotation is 0.08 s for the former and 0.09 s for the latter, and it has been found that the object can be achieved by rotating about 90 ° within approximately 0.09 s.

FIGS. 12 and 13 compare the arc characteristics of a TIG arc and a plasma arc at an arc current of 200 A.
The G arc has the advantage that the energy density is low, the arc shape is flat, and the temperature is low, whereas the plasma arc has a much higher energy density, and the high temperature arc has good elongation and the heat transfer efficiency is high. It can be said that the adoption of the plasma arc has enabled full-scale skull melting using a water-cooled metal crucible when dissolving a small amount of active metal.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method and apparatus for melting and pouring a metal according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic sectional side view showing one embodiment of a melting / injecting apparatus for achieving a method for melting / injecting an active metal according to the present invention.
FIG. 2 is a partial cross-sectional view taken along line AA in FIG. 1. In FIG. 1, the interior of the melting chamber 1 is made an inert gas atmosphere or a vacuum to melt an active metal such as titanium or zirconium on a metal crucible 4, and a melt 6 is provided below the melting chamber 1. The mold 21 is poured into a gate 22 of a mold 21 disposed in the mold 2. In this example, pure titanium was used as the molten metal, and a water-cooled copper crucible was used as the metal crucible.

In the melting / injecting apparatus shown in FIG. 1, a plasma torch 3 slidably suspended from the top of a melting chamber 1 and a molten metal are placed thereon, the melt 6 is held, and only the bottom is cooled. Therefore, the upper surface thereof is composed of a circular horizontal surface and an inclined surface surrounding the circular horizontal surface, and a melting means comprising a shallow dish-shaped metal crucible 4 having a cooling water passage 40 therein. And melt 6
Rotating means for retracting the melt 6 out of the fall trajectory prior to the vertical drop of the melt 6. The plasma torch 3 is connected to the (-) side of the DC power supply, and the water-cooled metal crucible 4 is connected to the (+) side.

Next, the rotating means for rotating the metal crucible 4 penetrates into the melting chamber 1 as shown in FIG.
A pair of horizontal metal tubes 7 fixed to the wall 11 of the melting chamber 1 and having a cooling water passage 70 therein,
A rotating shaft 41 of a water-cooled metal crucible 4 rotatably mounted on a bearing portion 71 at the tip of the crucible. It comprises a torsion coil spring 8 and a stopper 9 which holds the metal crucible 4 horizontally and can be disengaged. Therefore, the metal crucible 4 is disposed so as to be rotatable in a cantilever state about the rotation shaft 41 with respect to the horizontal metal tube 7.

The torsion coil spring 8 for rotating the metal crucible 4 has a left-right symmetrical form with an arm angle 90 ° having a long arm 81 and a short arm 82 as shown in FIG.
As shown in FIG. 4, a coil portion is mounted on the rotating shaft 41 of the metal crucible 4, and the long arm 81 is attached to the lower surface of the metal crucible 4 by the fixing tool 4.
4 and a pair of short arms 82 on the other end side are fixed to the wall 11 of the melting chamber 1 by fasteners 12 respectively. The stopper 9 is operated by a solenoid, and is engaged to hold the metal crucible 4 in a horizontal position, and is detached to rotate the metal crucible. Further, a mold 21 is placed on a mold elevating device 23 in the casting chamber 2.

Next, the steps of dissolving and injecting an active metal such as pure titanium using the method and apparatus for dissolving and injecting metal according to the present invention will be described with reference to FIGS. First, as shown in FIG.
Is lifted horizontally from the no-load hanging state, and the metal crucible 4
, The arm angle of the torsion coil spring 8 is urged from 90 ° to 180 °, the metal crucible 4 is horizontally supported by the stopper 9, and the pure titanium ingot 6M is placed on its horizontal surface. Next, the vacuum suction means 20 provided in the casting chamber 2 shown in FIG.
After completely replacing the air in the melting chamber 1 and the casting chamber 2 with high-purity argon gas by the gas supply means 10, the pressure is reduced to approximately 100 torr or less by vacuum suction.

Next, the plasma torch 3 and the ingot 6M
To generate a plasma arc 5 to start melting the pure titanium ingot 6M. Dissolve the ingot 6M
From the top to the bottom, but the melting proceeds
6 is sufficiently heated, a flat spherical melt 6 and a thin disk-shaped skull 6S are formed on the bottom surface as shown in FIG. 6B. When the stopper 9 is released by urging the solenoid at this stage, as shown in FIG. 6C, while the metal crucible 4 rotates downward by about 90 ° due to the restoration of the torsion coil spring 8, the center of gravity of the melt 6 Goes from G ₀ to G ₁ , the melt 6 falls vertically without touching any other object, and as shown in FIG. It is injected into the center of the gate 22.

In the above-mentioned embodiment, an integral symmetrical torsion coil spring 8 mounted on the back of the metal crucible 4 is used as a rotating means for rapidly rotating the metal crucible 4, but this is provided at the center by two. A similar effect can be obtained by using two split torsion coil springs.

In the above embodiment, the torsion coil spring 8 is used as the rotating means for rapidly rotating the metal crucible 4. However, the metal crucible 4 can be rotated by a driving device provided outside the melting chamber 1. It is. Another embodiment of the rotating means will be described with reference to FIGS. FIG.
7 is a partial sectional side view showing another embodiment of the rotating means according to the present invention, and FIG. 8 is a partial plan view of the rotating means shown in FIG.

A rotating means for rotating and braking the metal crucible 4 penetrates the wall 11 of the melting chamber 1 and has a cooling water passage 70 therein, and is screwed to the horizontal rotating shaft 17. Metal crucible 4 having cooling water passage 40 inside
And a rotary actuator 18 provided at the outside of the melting chamber 1 and having a swing angle of 90 ° for rotating the metal crucible 4 downward by 90 °. The rotating means is not limited to the rotating means described above, and has a function of rotating the metal crucible 4 downward by about 90 ° prior to the vertical drop of the molten material and retracting the metal crucible 4 out of the falling orbit of the molten material 6. If this is the case, it is of course possible to use other driving devices.

Although the metal crucible 4 has been described as an integral type in each of the above embodiments, an assembling method in which the metal crucible is divided into a main body 4 and a liner 4L as shown in FIG. In this case, the angle of inclination α between the circular horizontal surface 42 forming the upper surface of the metal crucible 4 and the inclined surface 43 surrounding the circular surface is constant, and the diameter D of the circular horizontal surface depends on the amount of the molten material.
It can be selected stepwise according to the diameter of the melting material (ingot).

It was also expected that the adhesive force between the molten material 6 and the skull 6S would cause the molten material 6 to receive a horizontal component force during rotation of the metal crucible 4, thereby preventing vertical falling. In the present invention, the flowability of the high-purity active metal melt was extremely good, and such an unfavorable situation did not occur.

[0035]

According to the present invention, when a plasma arc and a water-cooled metal crucible are used, the energy density of the arc can be kept extremely high, and more than a normal pressure of several tons.
A wide range of melting up to the orr vacuum region is possible, and a sufficiently heated melt of the active metal without any contamination can be stably obtained even in a small amount. The disc-shaped skull generated at the lower part of the melt is quenched by a water-cooled metal crucible, so it can be recovered without any contamination. be able to.

When melting is carried out in a non-water-cooled metal crucible, it is difficult to keep the melting conditions continuously constant due to a rise in the temperature of the metal crucible, which is one factor that hinders automation of the operation. However, when a plasma arc and a water-cooled metal crucible are used in the present invention, the metal crucible can be maintained at a constant temperature by the cooling water. Due to the difference from the constant heat loss carried away by the cooling water, heat is accumulated with time and the temperature of the melt rises. Therefore,
There is a certain relationship between the weight of the melting material and the melting time,
This can be quantified experimentally to contribute to the complete automation of operations.

Further, according to the present invention, since the skull is formed only on the bottom surface of the melt and not on the side surface, the ratio of the melt portion can be kept high, and the active metal melt can be moved from that position. Since it is dropped vertically without touching other objects on the way, a clean and high-temperature active metal melt can be directly injected into the center of the mold gate without heat loss due to contact. As a result, the effect of the flow of hot water to the tip of the product and the effect of the hot water can be remarkably improved, and the quality and yield of the product can be improved.

Further, in the injection means according to the present invention,
When a torsion coil spring is used to drive the water-cooled metal crucible, the rotating part is limited to only the water-cooled metal crucible, and since the torsion coil spring has both functions of rotation drive and braking, it is driven from outside the melting chamber. As compared with the case of using the braking means, no special driving source and transmission device are required, the structure is simple and light, and the equipment cost and the operating cost can be reduced. In addition, since the torsion coil spring is cooled and shielded by a water-cooled metal crucible in all portions including the coil portion, a normal torsion coil spring can be used without requiring a special heat-resistant spring.

[Brief description of the drawings]

FIG. 1 is a schematic side sectional view showing one embodiment of a melting / injecting apparatus for achieving a method for melting / injecting an active metal according to the present invention.

FIG. 2 is a partial cross-sectional view taken along line AA of FIG.

FIG. 3 is a perspective view showing an embodiment of a torsion coil spring used in the rotating means of the metal crucible according to the present invention.

FIG. 4 is a rear view showing a state in which the torsion coil spring of FIG. 3 is attached to a metal crucible.

FIG. 5 is an explanatory view showing the principle of skull dissolution of an active metal on a metal crucible according to the present invention.

FIGS. 6A to 6C are process diagrams of an embodiment for dissolving and injecting an active metal according to the present invention.

FIG. 7 is a partial sectional side view showing another embodiment of the rotating means of the metal crucible according to the present invention.

FIG. 8 is a partial plan view of the rotating means of FIG. 7;

FIG. 9 is a side sectional view showing another embodiment in which the metal crucible is of a split type in the present invention.

FIG. 10 is an explanatory diagram showing an analysis of a relative position between a free-falling melt and a metal crucible at the time of injection in the method of melting and injecting active metal.

FIG. 11 is another explanatory diagram when the rotation speed of the metal crucible in FIG. 10 is changed.

FIG. 12 is an explanatory diagram showing arc characteristics of a TIG arc.

FIG. 13 is an explanatory diagram showing arc characteristics of a plasma arc.

FIG. 14 is an explanatory view showing an example of a conventional active metal skull melting apparatus.

[Explanation of symbols]

 1: melting chamber 2: casting chamber 3: plasma torch 4: metal crucible 41: rotating shaft 5: plasma arc 6M: ingot 6: melt 6S: skull 7: horizontal metal tube 8: torsion coil spring 21: mold

Claims (6)

(57) [Claims] 1. A method for dissolving and pouring an active metal in an inert gas or vacuum using a metal crucible using a metal crucible and injecting a molten metal into a mold. Perform skull melting only by cooling the bottom,
Melt a flat spherical melt on a disk-shaped skull formed on a metal crucible, then rapidly rotate the crucible downward to move it out of the fall trajectory of the melt prior to the vertical drop of the melt. A method for dissolving and pouring an active metal, characterized by dropping a melt vertically from its position without touching other objects by retreating, and pouring the melt into the center of a mold gate. 2. An apparatus for dissolving and pouring an active metal in which a skull of an active metal is melted by setting the inside of a melting chamber to an inert gas atmosphere or vacuum, and a molten metal is injected into a mold gate disposed below. Melting means comprising: a generator, a dish-shaped metal crucible having an upper surface composed of a circular horizontal surface and an inclined surface surrounding the circular horizontal surface; and rapidly rotating the crucible downward to melt prior to the vertical drop of the melt. An active metal melting / injecting apparatus, comprising: rotating means for retracting the body out of a fall trajectory. 3. The diameter of a circular horizontal plane forming the upper surface of the metal crucible is Dcm, the angle of the inclined plane to the circular horizontal plane is α, the contact angle of the metal melt on the skull is β, and the weight of the molten metal material is Wgr. When, the D and ^{α, 0.45W 1/2 ≦ D ≦ 0.6W} 1/2 10 ° ≦ α < active metal according to claim 2, characterized in that in the range of 180 °-beta Dissolution / injection device. 4. The melting of active metal according to claim 2, wherein said melting means uses a plasma arc generator as an arc generator and a metal crucible having a cooling water passage therein. -Injection device. 5. A horizontal rotating shaft which penetrates into the wall of the melting chamber, is fixed to one end of the metal crucible, and allows cooling water to flow inside the metal crucible, and is provided outside the melting chamber. 3. A driving device for rotating a metal crucible substantially downward by 90 ° by rotating a metal crucible.
Infusion device. 6. A horizontal metal pipe which penetrates and is fixed to the wall of the melting chamber and circulates cooling water inside the metal crucible, a rotating shaft of the metal crucible rotatably attached to the horizontal metal pipe, The metal crucible is locked to the rotating shaft for substantially 90
3. The active metal melting / injecting apparatus according to claim 2, further comprising: a symmetric torsion coil spring rotated downward, and a stopper capable of being disengaged from the metal crucible.