JP3129076B2 - Floating melting apparatus and its tapping method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inductively heating a conductive material to be melted by placing it in an alternating magnetic field by electromagnetic induction and generating a magnetic field having a predetermined distribution to float the material to be melted by electromagnetic force. A flotation melting device capable of obtaining a high-purity material by applying a force to melt in a floating state, in particular, a small piece of solid material to be melted is continuously or intermittently charged from the upper portion, and an outlet provided at the lower portion The present invention relates to a flotation melting apparatus for taking out molten metal continuously or intermittently from a furnace and a method for tapping the same.

[0002]

2. Description of the Related Art In a levitation melting apparatus, a material to be melted is placed in an alternating magnetic field generated so as to have a predetermined distribution, and eddy current flowing through the material to be melted by electromagnetic induction is used for induction heating and electromagnetic force. And a buoyancy force, and simultaneously melt the material in a state where it does not come into contact with other objects such as a floating crucible to obtain a product having a predetermined material and dimensions. It has a high melting point and a high melting point because it has features such as extremely low contamination of foreign matter because it does not come into contact with other objects during melting, the ability to melt even materials with a high melting point, and a small heat conduction loss. It is used for dissolving materials requiring purity, for example, titanium and silicon.

There are various methods for taking out the product melted by the flotation melting apparatus. There is a method in which an outlet is provided at the bottom of the crucible and the molten metal is taken out continuously or intermittently from this outlet (Japanese Patent Laid-Open No. 5-15950). No.). According to this publication,
While melting the material in the crucible while controlling the current of the induction coil almost constant, a small piece of solid material is supplied continuously or intermittently from the top of the crucible, and the molten metal according to the supply amount is continuously supplied from the outlet. Alternatively, it is intermittently discharged and taken out, and injected into the next step such as pouring into a mold.

In this method, since the current is controlled to be constant as described above, the electromagnetic force such as the floating force generated in the molten metal is also constant. Therefore, the force for pushing the molten material from the outlet depends on the increase in gravity acting on the molten metal. That is, the weight of the molten metal is increased by the introduction of the small pieces of the solid material from above, and the molten metal is pushed out from the outlet.

[0005]

Incidentally, the specific gravity of a solid material is larger than that of a molten material of the same material. Therefore, after the small pieces are thrown in from the top, they may sink in the molten metal and reach the outlet. If the size of the small pieces is smaller than the size of the outlet, there arises a problem that insoluble material is taken out from the outlet. Further, if the size of the small pieces is larger than the outlet, there is a problem that the outlet is blocked even temporarily, and stable hot water cannot be supplied.

[0006] An object of the present invention is to solve such a problem and to provide a flotation melting apparatus capable of freely controlling the timing and amount of tapping and a tapping method therefor.

[0007]

According to the present invention, there is provided a bottomed cylindrical crucible in which segments made of a good conductive metal are laminated in a circumferential direction with an insulating plate interposed therebetween. An induction coil composed of two coils, an upper coil and a lower coil, provided on the outer diameter side of the slab, two AC power supplies for supplying current to the induction coil, and a small piece of conductive material to be melted continuously from the top of the crucible. In the flotation melting apparatus, which is provided with a charging device for charging the molten metal into the crucible and provided with an outlet for discharging the molten metal at the bottom of the crucible, the current of the lower coil is reduced when tapping the molten metal from the outlet. It shall be. The AC power supply for supplying a current to the lower coil employs a control method for keeping the power constant, and the frequency is controlled so that the lower coil and a power factor improving capacitor connected in parallel or in series with the lower coil resonate. In the flotation melting apparatus described in 1, the capacity of the power factor improving capacitor is reduced to reduce the current. Further, instead of reducing the current of the lower coil in the tapping method of the above-mentioned flotation and melting apparatus, the current of the upper coil is increased. In addition, the AC power supply that supplies current to the upper coil employs a control method of keeping the power constant, and the frequency is controlled so that the upper coil and the power factor improving capacitor connected in parallel or in series with the upper coil resonate. In the levitation melting apparatus, the capacity of the power factor improving capacitor is increased to increase the current. Also, instead of reducing the current of the lower coil in the tapping method of the above-mentioned flotation and melting apparatus, the upper coil is moved upward. In addition, a bottomed cylindrical crucible in which segments made of a good conductive metal are laminated in the circumferential direction via an insulating plate, one induction coil provided on the outer diameter side of the crucible, and an AC for supplying current to the induction coil A power supply, a continuous charging device for continuously charging small pieces of the conductive material to be melted into the crucible from the top of the crucible, and a flotation melting device provided with an outlet for taking out molten metal at the bottom of the crucible. The crucible has a shape in which the upper portion is narrowed by narrowing the upper portion of the crucible to increase the current of the induction coil when tapping. Further, a bottomed cylindrical crucible in which segments made of a good conductive metal are laminated in the circumferential direction via an insulating plate, an induction coil provided on the outer diameter side of the crucible, an AC power supply for supplying current to the induction coil, A continuous charging device for continuously charging small pieces of the conductive material to be melted into the crucible from the top of the crucible, and a floating melting device in which an outlet for taking out the molten metal is provided at the bottom of the crucible; It is assumed that a coil dedicated to tapping water is provided above the coil. In addition, instead of the coil dedicated to tapping of the flotation and melting apparatus described above, a gas supply device that blows inert gas from the upper part of the crucible is provided, and a downward force is applied to the molten metal by blowing the inert gas at the time of tapping. Shall be. In addition, the outlet is closed, and a stopper that can be freely opened and closed is provided, and the stopper is opened at the time of tapping. Further, the stopper is made of a water-cooled metal stopper or a conductive material having high resistance and high temperature resistance. A tapping control coil that is excited by an AC power supply is provided at a position around the tapping from the outlet, and the tapping is controlled by exciting the tapping control coil. Further, it is assumed that a tapping pipe through which a tapping section exiting from the outlet is passed, and a tapping control coil is provided on an outer diameter side of the tapping pipe. Also, the tapping tube is formed integrally with the crucible. Further, it is assumed that a crucible and an inlet / outlet of cooling water for cooling the tapping pipe are provided on a lower surface of the tapping pipe. It is assumed that the tapping pipe is insulated from the crucible.

[0008]

In the construction of the present invention, when the molten metal is taken out from the molten metal outlet provided at the bottom of the crucible,
When the current of the lower coil is reduced, the levitation force of the molten metal is approximately proportional to the square of the current of the lower coil, so that the levitation force is reduced and the position of the molten metal is lowered, so that the molten metal can be discharged.

In addition, a control method is employed in which an AC power supply for supplying a current to the lower coil keeps the power constant, and the frequency is controlled so that the lower coil and a power factor improving capacitor connected in parallel or series to the lower coil resonate. In this case, the current can be reduced by reducing the capacity of the power factor improving capacitor. That is, when the capacity of the power factor improving capacitor is reduced, the resonance frequency increases, and the actual frequency of the AC power supply increases to match the resonance frequency. Since the power loss generated in the molten metal or the crucible is substantially proportional to the square root of the frequency, the current is reduced as a result of controlling the power to be kept constant.

When the current of the upper coil is increased instead of decreasing the current of the lower coil in the above-described method of tapping the levitation and melting apparatus, the lateral drawing force of the molten metal is increased to become longer and thinner and the liquid on the lower surface of the molten metal becomes thinner. As the pressure rises and the downward electromagnetic force acting on the molten metal increases due to the positional relationship between the upper coil and the molten metal, the lower surface of the molten metal lowers and the molten metal can be discharged.

Further, a control system for maintaining a constant power in an AC power supply for supplying a current to the upper coil is employed, and the frequency is controlled so that the upper coil and a power factor improving capacitor connected in parallel or series to the upper coil resonate. In such a case, the current of the upper coil is increased by increasing the capacitance of the capacitor, contrary to the case of the lower coil described above. Also, instead of reducing the current of the lower coil in the tapping method of the above-mentioned levitation and melting apparatus, by moving the upper coil upward, the electromagnetic force for pressing the molten metal downward increases, and the position of the molten metal is lowered so that the molten metal is discharged. Will be possible.

Further, when the induction coil is formed of one coil, the crucible is formed into a shape in which the upper part thereof is squeezed to form an upper squeezed portion. The force increases and the melt becomes longer and thinner, but the upper surface approaches the upper drawing portion and is pressed downward by the repulsive force. As a result, the position of the lower surface of the molten metal is lowered, and the molten metal can be discharged. Also, a tapping-only coil is provided above the induction coil, and when the tapping is performed, a current flows through the tapping-only coil, so that the molten metal receives a downward force due to an electromagnetic force generated between the molten metal and the tapping-only coil. It becomes possible to drop hot water.

In addition, a gas supply device for blowing an inert gas from the upper part of the crucible is provided in place of the coil for exclusive use of hot water, and a downward force is applied to the molten metal by blowing the inert gas at the time of hot water so that the hot water is discharged. It can be possible.
In addition, the outlet is closed, and a stopper that can be freely opened and closed is provided.When the tap is not hot, the outlet is closed with this tap and the tap is opened at the time of tapping. As the stopper moves downward away from the outlet, it is sucked and the tap water is easily discharged from the outlet. In addition, if the plug is made of water-cooled metal, the eddy current flowing through the plug and the eddy current on the lower surface of the molten metal are in the same direction and attract each other, so that the suction of the molten metal by moving the plug downward is more reliable. become. In addition, since the plug is made of a conductive material having high resistance and high temperature resistance, the plug is overheated by the eddy current, so that the temperature of the lower surface of the molten metal which is close to the plug is further increased, the flowability is increased, and the molten metal is easily discharged. Become.

Further, a tapping control coil which is excited by an AC power supply is provided at a position surrounding the tapping portion from the outlet and no plug is provided, and the tapping control coil is excited to supply a current so that a tapping state can be obtained. Controls such as applying a horizontal drawing force to the hot water and cutting the hot water to cut the hot water to stop the hot water, or applying a floating force to the lower surface of the hot water when the hot water is not in the hot water state to stabilize the hot water can be performed. By providing a tapping pipe through which tapping water flows out of the outlet and a tapping control coil on an outer diameter side of the tapping pipe, the tapping control coil can be thermally cut off from tapping and its inductance can be reduced. Also,
Forming the tapping tube integrally with the crucible simplifies the structure. In this configuration, the crucible and the inlet / outlet of the cooling water for cooling the tapping pipe are provided on the lower surface of the tapping pipe, so that the arrangement of the induction coil and the tapping control coil is not hindered. Further, the tapping pipe may be insulated from the crucible and may be another one.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.
FIG. 1 is a schematic perspective view of a flotation melting apparatus according to a first embodiment of the present invention, in which a crucible 1 is omitted from the front half so that a molten metal 5 inside can be seen. In this figure, a crucible 1 has a bottomed cylindrical shape, is provided with slits equally spaced in the circumferential direction, and has an insulating plate inserted therein. Individual parts divided by the slits are called segments. ing.

An outlet 13 for taking out the molten metal to the outside is provided on the bottom surface of the crucible 1. An induction coil 20 composed of two coils, an upper coil 21 and a lower coil 22, is provided outside the crucible 1, and these coils 21, 22 are supplied with current by AC power supplies 31, 32, respectively. The crucible 1 is provided with a cooling pipe inside, and cooling water is supplied from the outside to be cooled strongly.

The molten metal 5 is melted and floated in the crucible 1 as shown. The levitation force necessary for floating the molten metal 5 is mainly due to the current of the lower coil 22. The upper coil 21 supplies electric power to the molten metal 5 by electromagnetic induction and applies an electromagnetic force to reduce the radius so as not to spread laterally. Such a force is called a lateral drawing force.

The AC power supplies 31 and 32 are high-frequency power supplies of several kHz or tens of kHz, rectify commercial power by a rectifier to obtain DC, and then obtain high-frequency power by an inverter. When a high-frequency current flows through the induction coil 20, an eddy current is generated in the crucible 1 and the molten metal 5 by electromagnetic induction, and the above-mentioned levitation force and lateral drawing force are generated by the electromagnetic force acting between the currents.

The molten metal 5 is enlarged by charging small solid pieces from the upper part of the crucible 1 by a charging device (not shown), and the molten metal 5 is discharged from the lower outlet 13 to be reduced as described later. The melt can be obtained continuously or intermittently by appropriately controlling the charging and discharging of the small pieces. FIG. 2 is a schematic perspective view showing a state in which the molten metal is discharged from the outlet 13 in the flotation melting apparatus of FIG.
Except in the hot water state, the configuration is the same as that of FIG. In order to change from the non-hot state of FIG. 1 to the hot state of FIG. 2, the lower surface of the molten metal 5 may be lowered, and for that purpose, the buoyancy may be reduced. The levitation force may reduce the current of the lower coil 22, whose main purpose is to generate the levitation force.

Incidentally, the AC power supplies 31 and 32 are controlled with high precision so that the molten metal 5 is stably maintained at a predetermined temperature and a floating state. In general, the control method is to keep the temperature and the levitation force constant by controlling the input power to be constant. Therefore, changing the current needs to break this method of constant power control. From this viewpoint, the following method can be used to reduce the current of the lower coil 22 in order to reduce the levitation force. At the time of tapping, the control method such as the constant power control adopted is released and switched to current control. If the frequency is controlled so that the power is constant and the inductance of the lower coil 22 and the capacitance of the power factor improving capacitor included in the AC power supply 32 are in a resonance state, the capacity of the capacitor is reduced and the current is consequently reduced. Smaller. The details are as follows. .

The inductance of the lower coil 22 changes depending on the size of the molten metal 5. Therefore, in order to effectively supply the electric power from the beginning of the operation, the frequency is controlled so that the power factor is always close to 1 according to the change in the size of the molten metal 5. As is well known, the resonance frequency increases when the capacity of the capacitor is reduced when tapping water. On the other hand, the crucible 1 and the molten metal 5 have a so-called remarkable skin effect, and the current flowing therethrough almost flows only near the surface thereof. In such a case, the power may be proportional to the square root of the frequency.
Therefore, as the frequency increases, the current is reduced and the power is kept constant.

According to this method, the levitation force required at the time of tapping can be reduced only by changing the capacity of the power factor improving capacitor included in the AC power supply 32. In general, several unit capacitors are connected in parallel via a switch so that the number of capacitors used can be appropriately controlled. Therefore, by using such a configuration, it is possible to perform the processing required for tapping as described above.

The upper coil 21 is used to reduce the buoyancy of the molten metal.
May be increased. That is, the electromagnetic force between the eddy current flowing on the upper surface of the molten metal 5 and the current of the upper coil 21 acts downward. Therefore, when the current of the upper coil 21 is increased, the downward electromagnetic force is increased and the levitation force is reduced. Further, as described above, since the upper coil 21 generates a lateral drawing force in the molten metal 5, the lateral drawing force is increased by increasing the current, and the upper coil 21 is elongated vertically, and the liquid pressure applied to the lower surface of the molten metal 5 is reduced. It rises and it becomes easy to take a bath.

The AC power supply 31 for the current of the upper coil 21 is also a lower coil.
Since the same configuration and control method as the AC power supply 32 of 22 are actually adopted, the method of increasing the current of the upper coil 21 is to switch the control method to current control, and to increase the capacitor when the frequency is controlled. One of the two methods of lowering the frequency.

FIG. 3 is a schematic perspective view of a flotation and melting apparatus according to a second embodiment of the present invention at the time of tapping. The same components as those in FIG. 2 are denoted by the same reference numerals, and detailed description thereof will be omitted. 3 is different from FIG. 2 in that the position of the upper coil 21 is moved upward in FIG. Do not change the current or frequency. In practice, the inductance changes when the lower coil 22 is moved upward, so that there is a change according to the control method used. For example, in the case of the above-described constant power control and frequency control methods, the frequency decreases because the inductance increases, and the current increases accordingly. However, in this embodiment, the main purpose is to move the position of the upper coil 21, and as a result, the change in the amount of electricity is dependent. When the upper coil 21 moves upward, the magnetic flux generated thereby also moves upward, the magnetic flux density on the upper surface of the molten metal 5 increases, the downward force increases, and the levitation force decreases. At this time, if the current increases simultaneously as described above, the influence on the levitation force acts additively. Therefore, the amount of movement of the upper coil 21 for securing the required amount of reduction in levitation force can be small.

The upper coil 21 is moved by the crucible 1 and the lower coil 22.
Any movement of the relative position with respect to is sufficient. Therefore,
Instead of moving the upper coil 21, the crucible 1 and the lower coil 22 may be moved downward together. Whichever is moved, a driving device and a control device for moving the moving device are required, and these can be easily realized by diverting the conventional technology.

FIG. 4 is a schematic perspective view of a flotation melting apparatus showing a third embodiment of the present invention. Like the previous figure, the same components as in FIG. Omit. The levitation melting device in this figure is one induction coil 2
And an AC power supply 3 for supplying current thereto. Upper coil 21 and lower coil as in the induction coil 20 described above.
An induction coil is formed by two coils 22 and 22 and each of them plays a main role. As shown in FIG. 4, one induction coil 2 serves as a levitation force, a lateral throttling force and a power supply. Is also adopted. FIG. 4 is different from the conventional one in that a tapping-only coil 23 and an AC power supply 33 thereof are provided in the configuration of such a conventional flotation melting apparatus.

The tapping coil 23 is provided above the induction coil 2. When the tapping is performed, a current is supplied by the AC power supply 33 so that a magnetomotive force is generated in the same direction as the induction coil 2. This is a phenomenon similar to increasing the current of the upper coil 21 in FIG. 3 or moving upward, and acts to reduce the buoyancy of the molten metal 5. Since the purpose is to use electromagnetic force, the frequency of the AC power supply 33 is actually lower than the frequency of the AC power supply 3.

FIG. 5 is a schematic perspective view of a flotation melting apparatus showing a fourth embodiment of the present invention. The same components as those in FIG. 4 are denoted by the same reference numerals, and detailed description thereof will be omitted. In this figure, an inert gas supply device is provided in place of the coil 23 dedicated to tapping water provided in the flotation and melting device of FIG. 4, and an inert gas 60 is blown out from above the crucible 1 to apply a downward force to the molten metal 5. Things. The upper part of the crucible 1 is covered with a gas guide lid 6 and hermetically sealed and connected to a gas storage device (not shown) by a pipe. At the time of tapping, the electromagnetic valve of the pipe is opened to blow out the inert gas 60 and hit the upper part of the molten metal 5. This allows the molten metal 5
The downward force works on the hot water.

As the inert gas 60, a so-called inert gas such as argon or helium is suitable. However, since these are expensive, nitrogen gas may be sufficient depending on the material of the molten metal 5. FIG. 6 is a schematic perspective view of a flotation melting apparatus according to a fifth embodiment of the present invention. In this figure, the crucible 1
A has a shape in which the upper part is squeezed similarly to the lower part, and the schematic cross-sectional shape of the crucible 1A is U-shaped. However, since it is necessary to input a small solid piece from the upper portion as described above, an input port without a reference numeral is provided for that.

The figure shows a tapping state, in which tapping section 51 is taken out of outlet 13. That is, the current of the induction coil 2 is increased to make the hot water. Induction coil 2
When the current is increased, the levitation force increases in a normal crucible and the molten metal 5 does not enter the hot-water state, but the horizontal drawing force increases and the molten metal 5 becomes elongated vertically. Since the crucible 1A is provided with the upper constricted portion 12, when the molten metal 5 is elongated and its upper surface approaches the upper constricted portion 12, currents in opposite directions flow as shown in the figure in the figure. Therefore, the repulsive force works to generate a downward force. Since the liquid pressure on the lower surface of the molten metal 5 rises due to the elongation by the horizontal drawing force, and the upper drawn part 12 limits the movement of the molten metal 5 upward. You can go down to the hot water state.

Since the crucible 1 can be brought out of hot water by providing the upper throttle portion 12, there is no need to provide the upper throttle portion 12 or attach a device for blowing the inert gas 60 as described above. In addition, the method of making the tapping state by simply reducing the current of the induction coil 2 to reduce the levitation force has a problem that the temperature of the molten metal 5 is lowered because the input power becomes small. Such a problem in which the upper throttle section 12 is provided does not cause such a problem. 2
In the case of a levitation and melting apparatus provided with an induction coil 20 composed of two coils, the lower coil 22 reduces the current at the time of tapping and the upper coil 21 supplies power to the molten metal 5 mainly. However, the problem that the temperature of the molten metal 5 actually lowers does not occur.

FIG. 7 is a schematic perspective view of a levitation and melting apparatus according to a sixth embodiment of the present invention in a non-hot state, and FIG. 8 is a schematic perspective view of the levitation and melting apparatus in a molten state. In these figures, the shape of the crucible 1 is basically the same as the other figures except FIG. 6, and the induction coil 2 and its AC power supply 3 are the same as those in FIG. The difference between these figures and the other figures is that
Is provided. When the tap 7 is not in the hot water supply state, it is inserted into the outlet 13 as shown in FIG. At the time of tapping, when the lower surface of the molten metal 5 comes down and approaches or comes into contact with the outflow port 13 by various methods as described above, the stopper 7 is moved downward and separated from the outflow port 13. At this time, the stopper 7 functions to suck or pull out the molten metal 5 to the outlet 13.

The stopper 7 is made of either water-cooled metal or a conductor material having high resistance and high temperature resistance such as graphite. When the plug 7 is made of water-cooled metal, when the molten metal 5 goes down and its lower surface approaches and comes into contact with the plug 7, the contact surface solidifies and adheres to the plug 7. When the stopper 7 is moved downward in this state, the lower surface of the molten metal 5 is drawn into the outlet 13 together with the solidified portion. Since an eddy current flows through the plug 7 in the same direction as the molten metal 5, the current attracts each other to draw the molten metal 5 to the outlet 13 even if the lower surface of the molten metal 5 does not adhere to the plug 7.

When the plug 7 is made of a high resistance and high temperature resistant material such as graphite, the temperature of the plug 7 rises due to the eddy current flowing through the plug 7. Therefore, the temperature of the lower surface of the molten metal 5 approaching the stopper 7 is further increased, the fluidity is increased, and the molten metal is easily discharged from the outlet 13. The stopper 7 functions to assist the molten metal 5 to easily flow out of the outlet 13 as described above, but closes the outlet 13 when the molten metal is not flowing out, so that a small piece of solid injected from the top remains solid. There is also an effect that the stopper 7 does not come out of the outlet 13 because the plug 7 exists when the sinker 5 reaches the sinking bottom and tries to drop further.

FIG. 9 is a schematic perspective view of a floating and melting apparatus according to a seventh embodiment of the present invention in a tapping state, and FIG. 10 is a schematic perspective view of the same floating and melting apparatus when tapping is completed. . The difference between FIGS. 7 and 8 in these figures is that the stopper 7
A tapping pipe 82 following the outlet 13 and a tapping control coil 81 that is excited by an AC power supply 83 and supplied with current are provided on the outer diameter side of the tapping pipe 82.

In order to stop the molten metal from the state shown in FIG. 9 and bring it into a non-molten state, the molten metal 5 is raised, but at this time, the molten metal part 51 is not necessarily cut off easily. When a current is supplied to the tapping control coil 81 when the tapping is stopped, a lateral drawing force acts on the tapping section 51. This horizontal drawing force makes the tapping section 51 thin and easy to cut, and furthermore, a portion of the tapping section 51 above the center position of the tapping control coil 81 acts on an upward direction, and a portion below the tapping section has a downward direction. Since the force is applied, it eventually breaks as shown in FIG. 10 and the tapping stops. The frequency of the AC power supply 83 does not necessarily need to be the same as that of the AC power supply 3, and a frequency suitable for cutting the tapping section 51 may be selected. It is to be noted that the levitation force of the molten metal 5, particularly at the lower portion thereof, can be increased by passing an electric current through the tapping control coil 81.
Can be used to stably float the molten metal 5 by supplying an electric current thereto. Further, it is also possible to reduce the buoyancy of the molten metal 5, particularly the lower surface thereof, by flowing a current in the opposite direction at the same frequency as that of the induction coil 2 so as to promote the molten metal.

The reason for providing the tapping pipe 82 is as follows. Hot water supply control coil 83 is thermally disconnected from hot water supply section 51. The inductance of the tapping control coil 83 is reduced. Therefore, thermal insulation is provided by providing a tubular heat insulating material to deal with the increase in inductance separately.
The provision of 82 can be omitted. The tapping pipe 82 in the figure is formed integrally with the crucible 1 of the above-described embodiment, and forms a crucible 1B that is put together. Therefore, the thickness dimension of tapping pipe 82 is also the same as crucible 1. The reason why such a configuration is adopted is to provide an inlet / outlet for cooling water to enter / exit a cooling pipe provided inside the crucible 1 on the lower surface of the tapping pipe 82. Of course, it is possible to adopt a rational configuration that does not hinder the arrangement of the tapping control coil 82. When the cooling water inlet / outlet of the crucible 1 is provided separately, the thickness dimension of the tapping pipe 82 may be thinner, and may be such that the original function of the tapping pipe 82 is satisfied.

FIG. 11 is a schematic perspective view of a floating and melting apparatus according to an eighth embodiment of the present invention in a tapping state, and FIG. 12 is a schematic perspective view of the same floating and melting apparatus when tapping is completed. The difference between these figures and Figures 9 and 10
82C is configured separately from the crucible 1C. As described above, when the configuration in which the cooling water outlet is provided in the tapping pipe 82 is not adopted, there is no necessity to integrate the crucible 1C and the tapping pipe 82C, and thus the crucible 1C and the tapping pipe 82C are not necessary.
A configuration in which the components are insulated from each other can be adopted.
At this time, as described above, the thickness of tapping pipe 82C may be a dimension necessary for the function. However, tapping pipe 82C needs to be cooled by a cooling structure different from crucible 1C.
Such a tapping pipe 82C may be used in a configuration different from that of the crucible 1C when the existing flotation and melting apparatus is configured without the tapping pipe 82C to add the tapping pipe 82C to improve the function. it can.

The tapping control coil 81 and tapping pipe 82 or tapping pipe 82
The configuration in which C is provided can be applied to all the above-described inventions except for the configuration in which the stopper 7 in FIGS. 7 and 8 is provided.

[0041]

As described above, according to the present invention, in the case of a levitation melting apparatus in which an induction coil is composed of two coils, an upper coil and a lower coil, an outlet for discharging molten metal provided at the bottom of a crucible. When the current of the lower coil is reduced when the molten metal is taken out of the furnace, the buoyancy is reduced because the levitation force of the molten metal is approximately proportional to the square of the current, and the molten metal is lowered in position to be able to tap. Therefore, by controlling the current of the lower coil, the tapping can be performed when the tapping is desired.When a small piece of solid is poured from above, the non- tapping state is maintained so that the small piece does not melt and remains solid. The effect is obtained that the molten metal does not reach the lower part of the molten metal and block the outlet at the time of the molten metal, and does not flow out as a solid.

Also, a control method is employed in which an AC power supply for supplying a current to the lower coil keeps the power constant, and the frequency is controlled so that the lower coil and a power factor improving capacitor connected in parallel or series thereto resonate. In such a case, if the capacity of the power factor improving capacitor is reduced, the resonance frequency increases, and the frequency of the AC power supply increases accordingly. Since the loss that occurs in the molten metal is proportional to the square root of the frequency, a control to reduce the current acts to keep the power constant, and as a result, the buoyancy of the molten metal decreases, and the same effect as described above is obtained. Can be

When the current of the upper coil is increased instead of decreasing the current of the lower coil in the above-described method of tapping the levitation and melting apparatus, the lateral drawing force of the molten metal is increased to be elongated, and the liquid on the lower surface of the molten metal is elongated. As the pressure rises and the downward electromagnetic force acting on the molten metal increases due to the positional relationship between the upper coil and the molten metal, the lower surface of the molten metal is lowered and the molten metal can be discharged, and the same effects as described above can be obtained.

Further, a control method is employed in which an AC power supply for supplying a current to the upper coil maintains a constant power, and the frequency is controlled so that the upper coil and a power factor improving capacitor connected in parallel or in series with the upper coil resonate. In this case, the same effect can be obtained because the current of the upper coil is increased by increasing the capacitance of the capacitor, contrary to the case of the lower coil.

Also, instead of reducing the current of the lower coil in the method of tapping the levitation and melting apparatus described above, by moving the upper coil upward, the electromagnetic force pressing the molten metal downward increases, thereby lowering the position of the molten metal. The same effect can be obtained. Also, in the case of a flotation and melting apparatus in which the induction coil is composed of a single coil, the crucible is squeezed at its upper portion to form an upper squeezed portion. As a result, the molten metal becomes longer and thinner, and the upper surface thereof approaches the upper drawing portion and is pressed downward by the repulsive force. As a result, the position of the lower surface of the molten metal is lowered and the molten metal can be discharged, and the same effect can be obtained.

Also, a tapping coil is provided above the induction coil, and when the tapping is performed, an electric current flows through the tapping coil so that the molten metal receives a downward force due to an electromagnetic force generated between the molten metal and the tapping coil. The position is lowered and hot water can be discharged, and the same effect can be obtained. In addition, instead of a coil dedicated to tapping, a gas supply device that blows inert gas from the top of the crucible is provided, and by blowing the inert gas at the time of tapping, a downward force is given to the molten metal to enable tapping. You can also.

Further, the outlet is closed, and a stopper that can be freely opened and closed is provided. When the hot water is not supplied, the outlet is closed and the tap is opened at the time of tapping. The lower surface of the stopper is sucked or pulled as the stopper moves downward away from the outlet, so that the hot water can be easily discharged from the outlet. Also, if the stopper is made of water-cooled metal,
Since the portion in contact with the plug is solidified and adhered, and the eddy current flowing through the plug and the eddy current on the lower surface of the molten metal are in the same direction, they are attracted to each other. Therefore, the suction of the molten metal by moving the plug downward is more reliable. In addition, since the plug is made of a conductive material having high resistance and high temperature resistance, the plug is overheated by the eddy current, so that the temperature of the lower surface of the molten metal which is close to the plug is further increased, the flowability is increased, and the molten metal is easily discharged. Is obtained.

In addition, no tap is provided, but a tapping control coil excited by an AC power supply is provided at a position orbiting the tapping section from the outlet, and the tapping control coil is excited to supply a current so that the tapping state is maintained. It can be controlled by giving a horizontal drawing force to the hot water and cutting it to cut it to stop the hot water, or when the hot water is not in the hot water state, it can apply floating power to the lower surface of the hot water to stabilize the hot water and so on. This has the effect of contributing to tapping work of the melting device and stabilization of the floating bath. Also,
By providing a tapping pipe for passing tapping water from the outlet on the inner diameter side of the tapping control coil, the tapping control coil can be thermally shielded from tapping by the tapping pipe and its inductance can be reduced. Further, the structure is simplified by forming the tapping tube integrally with the crucible, and in this configuration, the crucible and the inlet / outlet of the cooling water for cooling the tapping tube are provided on the lower surface of the tapping tube, so that the induction coil and the tapping control coil are provided. The effect that the arrangement does not disturb the arrangement can be obtained.
In addition, the tapping pipe may be another one insulated from the crucible. With this configuration, the function can be improved by adding the tapping pipe and tapping control coil to the existing flotation and melting apparatus.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a flotation melting apparatus showing a first embodiment of the present invention.

FIG. 2 is a schematic perspective view showing a tapping state of the flotation melting apparatus of FIG. 1;

FIG. 3 is a schematic perspective view of a flotation melting apparatus according to a second embodiment of the present invention at the time of tapping.

FIG. 4 is a schematic perspective view of a flotation melting apparatus showing a third embodiment of the present invention.

FIG. 5 is a schematic perspective view of a flotation melting apparatus showing a fourth embodiment of the present invention.

FIG. 6 is a schematic perspective view of a flotation melting apparatus showing a fifth embodiment of the present invention.

FIG. 7 is a schematic perspective view of a flotation melting apparatus according to a sixth embodiment of the present invention in a non-hot state;

FIG. 8 is a schematic perspective view of the same flotation apparatus as in FIG. 7 in a tapping state.

FIG. 9 is a schematic perspective view of a flotation and melting apparatus according to a seventh embodiment of the present invention in a hot-water supply state.

FIG. 10 is a schematic perspective view at the time when the tapping of the same flotation apparatus as in FIG. 9 is completed.

FIG. 11 is a schematic perspective view of a flotation and melting apparatus according to an eighth embodiment of the present invention in a tapping state.

FIG. 12 is a schematic perspective view of the same levitation and melting apparatus as in FIG. 11 at the time when tapping is completed.

[Explanation of symbols]

1, 1A, 1B, 1C Crucible 12 Upper drawing part 13
Outlet 2, 20 Induction coil 21 Upper coil 22 Lower coil 23 Dedicated tapping coil 3, 31, 32, 33 AC power supply 5 Melt 51 Tapping section 6 Gas guide lid 60 Inert gas 7 Plug 81 Tapping control coil 82, 82C Tapping pipe 83 AC power supply

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI F27D 11/06 F27D 11/06 A (56) References JP-A-5-15950 (JP, A) JP-A-5-3075 ( JP, A) JP-A-61-93383 (JP, A) JP-A-2-52094 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H05B 6/32 F27B 14/00 F27D 11/06

Claims (18)

(57) [Claims] 1. A bottomed cylindrical crucible in which segments made of a good conductive metal are laminated in a circumferential direction via an insulating plate, and two coils of an upper coil and a lower coil provided on the outer diameter side of the crucible. Supply current to the induction coil consisting of
Levitation melting apparatus comprising: an AC power source; a charging device for continuously charging small pieces of a conductive material to be melted into the crucible from the top of the crucible; and an outlet for discharging molten metal is provided at the bottom of the crucible. Wherein the current of the lower coil is reduced when the molten metal is taken out from the outlet. 2. An AC power supply for supplying a current to the lower coil employs a control method for keeping the power constant, and the frequency is controlled so that the lower coil and a power factor improving capacitor connected in parallel or series thereto resonate. 2. The method according to claim 1, wherein the capacity of the power factor improving capacitor is reduced to reduce the current. 3. A tapping method for a levitation and melting apparatus according to claim 1, wherein the current in the upper coil is increased instead of decreasing the current in the lower coil. 4. An AC power supply for supplying a current to the upper coil employs a control method for keeping the power constant, and the frequency is controlled so that the upper coil and a power factor improving capacitor connected in parallel or series thereto resonate. 4. The method according to claim 3, wherein the capacity of the power factor improving capacitor is increased to increase the current. 5. A tapping method for a levitation and melting apparatus according to claim 1, wherein the upper coil is moved upward instead of reducing the current of the lower coil in the tapping method of the levitation and melting apparatus. 6. A bottomed cylindrical crucible in which segments made of a good conductive metal are laminated in a circumferential direction via an insulating plate, a single induction coil provided on the outer diameter side of the crucible, and a current flowing through the induction coil. An AC power supply, a continuous charging device for continuously charging small pieces of conductive material to be melted into the crucible from the top of the crucible, and a flotation having an outlet for taking out molten metal at the bottom of the crucible. A flotation melting apparatus characterized in that a crucible shape is formed by narrowing an upper portion of the crucible to form an upper throttle portion, and an induction coil capable of increasing current when tapping is provided. 7. A bottomed cylindrical crucible in which segments made of a good conductive metal are laminated in the circumferential direction via an insulating plate, an induction coil provided on the outer diameter side of the crucible, and a current supplied to the induction coil. An AC power supply, a continuous charging device for continuously charging small pieces of the conductive material to be melted into the crucible from the top of the crucible, and a flotation / melting device provided with an outlet for taking out molten metal at the bottom of the crucible. 3. A flotation and melting apparatus according to claim 1, wherein a coil dedicated to tapping is provided above the induction coil. 8. A gas supply which can blow an inert gas which gives a downward force to the molten metal by blowing an inert gas at the time of tapping from the upper portion of the crucible instead of the tapping coil according to claim 7. A flotation melting device characterized by providing a device. 9. The system according to claim 1, wherein the outlet is closed and a stopper is provided which can be freely opened and closed. The levitation melting apparatus according to any one of claims 8 to 10. 10. The method according to claim 9, wherein the tap is opened at the time of tapping. 11. The flotation melting apparatus according to claim 9, wherein said stopper is a water-cooled metal stopper. 12. The flotation melting apparatus according to claim 9, wherein the stopper is made of a conductive material having high resistance and high temperature resistance. 13. A tapping control coil excited by an AC power supply is provided at a position surrounding a tapping section from an outlet.
The levitation melting apparatus according to any one of claims 5, 6, and 8. 14. A tapping method for a levitation and melting apparatus according to claim 13, wherein tapping is controlled by exciting a tapping control coil. 15. The flotation and melting apparatus according to claim 13, further comprising a tapping pipe through which tapping water from the outlet is passed, and a tapping control coil provided on an outer diameter side of the tapping pipe. 16. The flotation melting apparatus according to claim 15, wherein the tapping pipe is formed integrally with the crucible. 17. The flotation and melting apparatus according to claim 15, wherein a crucible and an inlet / outlet of cooling water for cooling the tapping pipe are provided on a lower surface of the tapping pipe. 18. The flotation melting apparatus according to claim 13, wherein the tapping pipe is insulated from the crucible.