JP2002327219A - Method for melting metal, and metal melting device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for melting metal, which can apply an anti-gravity casting such as semi-levitation melting and reduced-pressure suction casting even to ferrous metals, and also provide a metal melting device therefor. SOLUTION: The metal melting device 1 includes a side wall 4 consisting of a water-cooled segment 4a made of electrically insulated copper or the like, a crucible 2 with a basilar part of a ceramic 8, a high-frequency induction coil 14 wound up at spaces around the outside of the crucible 2, a power supply 16 for supplying power to the high-frequency induction coil 14, the control means 18 for controlling electric power cast into the high-frequency induction coil 14 from the power supply 16, and a ceramic mold 40 located above the crucible 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for melting various metals or alloys by induction heating to melt them in a semi-floating state and to perform antigravity casting.

[0002]

2. Description of the Related Art A melting apparatus 20 as shown in FIG. 4 is used for melting and precision casting a titanium alloy in a semi-floating state. As shown in FIG.
A water-cooled crucible 22 for charging a raw material titanium alloy, a guide 30 placed on the crucible 22, a chamber 35 arranged in the guide 30 so as to be able to move up and down, and a ceramic mold arranged in the chamber 35 40 is provided. As shown in FIG. 4, the water-cooled crucible 22 includes a cylindrical side wall 24 and a bottom wall 26 made of copper, and a raw material titanium alloy is charged into an inside 23 surrounded by these. A plurality of insulating slits (not shown) are formed at equal intervals in the side wall 24 along the vertical direction, and cooling water circulates in each segment interposed between these slits.

A high-frequency induction coil 28 is spirally wound around the water-cooled crucible 22 at intervals, and a cylindrical guide 3 is placed on the water-cooled crucible 22.
0 is placed. The guide 30 includes a side wall 31 and a bottom wall 3.
And the water-cooled crucible 22 in the center of the bottom wall 32.
Has an opening 33 that communicates with the inside 23 of the inside. Furthermore,
As shown in FIG. 4, a box-shaped chamber 35 is arranged inside the guide 30 so as to be able to move up and down by an elevating means (not shown). The chamber 35 has a through hole 37 through which the nozzle 29 penetrates in the center of the bottom surface of the cylindrical main body 36, and has a suction hole 39 in the center of the cover plate 38. An air-permeable ceramic mold 40 is set in the chamber 35. The mold 40 has a base end portion 42 having a substantially Y-shaped runner 46 communicating with the nozzle 29 therein, a plurality of branch portions 44 extending obliquely upward from the upper end thereof, and
4 and a product portion 48 having cavities C1, C2,... Individually.

[0004] In the state shown in FIG.
, And a required high-frequency current is supplied to the high-frequency induction coil 28. Then, the coil 28 concerned
Is formed around the crucible 22 and the inside 2
When the titanium alloy penetrates into the titanium alloy of No. 3, the titanium alloy is heated and melted by Joule heat generated by a skin current induced on the surface. In the molten metal M of the titanium alloy, an induced current is induced by the coil 28 and flows, and due to a repulsive force (Lorentz repulsion) generated between these currents, as shown in FIG.
The inner side 23 of the crucible 22 is separated from the side wall 24 and rises upward to be in a semi-floating state. In addition, molten metal M
Is cooled by contacting the side wall 24 and the bottom wall 26 of the crucible 22, so that solidified shells S1 and S2 are formed below the inner surface 25 of the side wall 24 and on the bottom surface 27 of the bottom wall 26, respectively.

[0005] As shown in FIG. 4, the inside 34 of the guide 30 is filled with argon gas in advance, and a suction hole 39 is provided.
When the inside of the chamber 35 is depressurized and depressurized, the molten metal M in a semi-floating state rises through the nozzle 29 and is
Are cast into the cavities C1, C2,... Of each product section 48. Then, the mold 4 taken out by opening the lid plate 38
By varying 0, a titanium alloy precision cast product having a shape following the cavities C1 and C2 can be obtained.

[0006]

SUMMARY OF THE INVENTION A dissolving apparatus 20 as described above
By combining semi-floating melting with reduced pressure suction casting, which is one of antigravity casting, high melting point active metals such as titanium can be efficiently melted in a non-contaminated state and precision cast. Further, the melting device 20 can be applied to metals and alloys other than titanium. However, when the melting apparatus 20 is applied to an iron-based metal to manufacture a precision casting product, the power cost required for semi-floating melting becomes excessive, and the product cost also increases, which is not practical. For this reason, there was a problem that the melting and casting method combining semi-levitation melting and antigravity casting is difficult to apply to ferrous metals. The present invention solves the conventional problems as described above, and, even for an iron-based metal, a method for melting a metal to which anti-gravity casting such as semi-levitation melting and vacuum suction casting can be applied, and a metal used for the method. It is an object to provide a melting device.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention reduces the contact area between a crucible and a molten metal, suppresses heat removal from the molten metal during semi-floating melting, and inputs heat to the molten metal. It was made with the idea of balancing. That is, the metal melting method of the present invention (Claim 1)
The induction heating of the metal charged in the crucible and the molten metal is cast into a mold above the crucible against gravity, and the side wall of the crucible is made of a water-cooled segment such as copper, which is electrically insulated. A method for melting a metal using a melting device in which the bottom of the crucible is made of ceramic, wherein the top of the molten metal charged in the crucible and heated by induction is levitated by electromagnetic induction repulsion, and the molten metal is melted. By contacting the lower side surface of the crucible with the water-cooled segment of the side wall of the crucible and balancing the heat removal by the contact and the heat input by the induction heating, the metal is melted while keeping the temperature of the molten metal constant. , Characterized in that.

[0008] According to this, the bottom of the crucible is insulated.
By forming with a lamic, heat removal from the molten metal
It is possible to suppress the heat removal and heat input by induction heating.
At equilibrium at relatively low levels, the molten metal
The metal can be melted while keeping the temperature constant.
You. Therefore, even with iron-based metals, power costs and
Because the manufacturing cost resulting from this can be reduced, the
Anti-gravity casting such as melting and vacuum suction casting
This can be performed at a practical level. In addition, the above Sera
Mick has spinel (Al₂O₃, MgO), alumina
(Al₂O ₃), Magnesia (MgO), or mullite
(SiO₂, Al₂O₃) Or a mixture of these
Is included.

In the present invention, in order to balance the heat removal and the heat input at an arbitrary level, the input power required for the induction heating is controlled to increase or decrease the heat input, whereby the molten metal is increased. The present invention also includes a metal melting method (Claim 2) for changing the floating state of the molten metal and changing the contact area between the molten metal and the side wall of the crucible to increase or decrease the heat removal. According to this, since the contact area between the molten metal and the crucible changes, heat removal from the molten metal and heat input required for induction heating can be reliably balanced at an arbitrarily low level. Therefore, stable semi-floating melting and anti-gravity casting can be performed while suppressing the power cost.

On the other hand, the metal melting apparatus of the present invention used in the above melting method (Claim 3) comprises: a crucible including a side wall made of an electrically insulated water-cooled segment made of copper or the like and a bottom made of ceramic; A high-frequency induction coil wound around the crucible at intervals, a power supply for supplying power to the high-frequency induction coil, control means for controlling power supplied from the power supply to the high-frequency induction coil, And a mold located at According to this, since the bottom portion of the crucible is formed of a heat insulating ceramic, heat extraction from the molten metal can be suppressed. In addition, by increasing or decreasing the output of the power supply under the control of the control means, the heat removal and the heat input by induction heating are balanced at a relatively low level, and the temperature of the molten metal is kept constant. Can dissolve metals.

[0011] Therefore, even with iron-based metals, the power cost and the resulting manufacturing cost can be reduced, so that precise antigravity casting by melting in a semi-floating state and vacuum suction casting is performed practically. It becomes possible. Note that the control means includes a form such as an accessory part of a power supply having only a function of simply increasing or decreasing the output of the power supply.
Alternatively, data on the characteristics of the metal or alloy to be melted, data on the amount of heat input required for induction heating and melting of these molten metals, and data on the equilibrium state of heat removal due to contact between the molten metal and the crucible are stored in advance. In addition, a mode (a computer or the like) for calculating and instructing a pattern for increasing or decreasing the output of the power supply in the shortest time according to the temperature of the molten metal or the like is also included.

Further, according to the present invention, there is provided a metal melting apparatus in which a water cooling segment forming a side wall of the crucible has an inner surface facing the inside of the crucible tapered upward. Is also included. According to this, it is possible to easily remove, from the crucible, the solidified metal remaining in the portion of the molten metal that has come into contact with the crucible. As a result, the cycle time required for each melting and casting can be reduced, so that the manufacturing cost can be further reduced. Moreover, since the crucible can be prevented from being contaminated, the crucible can be easily used for dissolving dissimilar metals.

Further, the present invention also includes a metal melting device in which an airtight seal is arranged along the outer periphery of the water cooling segment forming the side wall of the crucible.
According to this, only the crucible can be sealed in an airtight state, so that the holding of the atmospheric gas in the crucible and the evacuation become easy. Therefore, there is no need to form a vacuum chamber surrounding the entire melting apparatus including the antigravity casting means including the mold located above the crucible and the high-frequency induction coil outside the crucible. For the hermetic seal, a resin having both insulating properties and ease of molding, for example, a phenol resin (trade name: Bakelite) is used.

[0014]

Preferred embodiments of the present invention will be described below with reference to the drawings. In the following, the same reference numerals are used for the elements and parts similar to those shown in FIG. 1 and 3 are vertical sectional views showing a main part of a metal melting apparatus 1 according to the present invention. The melting device 1 is shown in FIG.
As shown in FIG. 1, a crucible 2 for charging a ferrous metal as a raw material, a high-frequency induction coil 14 wound spirally outside the crucible 2, a power supply 16 for the coil 14, and a control means 18 for the power supply 16 It has. FIG.
As shown in FIG. 2, the melting apparatus 1 includes a guide 30 placed on the crucible 2, a chamber 35 arranged in the guide 30 so as to be able to move up and down, and a ceramic mold 40 arranged in the chamber 35. It has.

As shown in FIGS. 1 and 2A and 2B,
The crucible 2 has a substantially cylindrical side wall 4 made of pure copper, a disc-shaped ceramic 8 disposed at the bottom of the inner side 3 of the crucible 2, and is surrounded by a lower end 7 of the side wall 4 and located below the ceramic 8. Bottom wall 10. The bottom wall 10 also has a disc-shaped hollow structure made of pure copper and the inside of which is water-cooled. The ceramic 8 is made of, for example, spinel (Al
₂ O ₃ , MgO), diameter 200 mm x thickness 40 m
m. FIG. 2 (A),
As shown in (B), the side wall 4 of the crucible 2 has a plurality of insulating slits 6 formed at regular intervals in the circumferential direction along the vertical direction, and is electrically insulated along the circumferential direction. ing. Further, in a large number of water cooling segments 4a, 4a,... Sandwiched between the adjacent insulating slits 6, 6, water passage holes 4b are individually formed along the vertical direction, and the cooling water W is supplied to each of the water passage holes 4b. By circulating through the inside, overheating of the crucible 2 itself due to induction heating described later is prevented.

Further, as shown in FIGS. 1 and 2A and 2B, an inner surface 5 facing the inner side 3 of the side wall 4 of the crucible 2.
Is tapered so as to be several degrees wider from the ceramic 8 located at the bottom toward the opening at the upper end. As shown in FIG. 1, a hermetic seal 12 made of a phenol resin and having a thickness of several mm to 10 mm is wound around the outer peripheral side of the side wall 4 of the crucible 2. An induction coil 14 is wound. Both ends of the coil 14 are electrically connected to a high-frequency current power supply 16 as shown by a solid line in FIG. 1, and a control means 18 for adjusting the output of the power supply 16 is arranged adjacent to the power supply 16.

As shown in FIG. 3, the above-mentioned crucible 2
The same guide 30 as described above is placed above, and a chamber 35 is arranged inside the guide 30 so as to be able to move up and down.
0 is arranged. As shown in FIG. 3, the guide 30 has a side wall 31 and a bottom wall 32, and has an opening 33 communicating with the inside 23 of the crucible 2 at the center of the bottom wall 32. A box-shaped chamber 35 which can be moved up and down by an elevating means (not shown) is provided inside 34 of the guide 30.
Is arranged.

The chamber 35 has a through hole 37 through which the nozzle 29 penetrates in the center of the bottom surface of the box-shaped main body 36, and has a suction hole 39 in the center of a cover plate 38 which closes the opening at the upper end. An air-permeable ceramic mold 40 is set in the chamber 35. The mold 40 includes a base end portion 42 in which a substantially Y-shaped runner 46 communicating with the nozzle 29 made of steel pipe is provided, a plurality of branch portions 44 extending obliquely upward from the upper end thereof, and tips of the branch portions 44. , And individually having cavities C1, C2,...
Consists of

In the state shown in FIGS.
Approximately 50 kg of an iron-based metal is charged into the device, and a required high-frequency current is supplied from the power supply 16 to the high-frequency induction coil 14. Then, the magnetic field formed around the coil 14 becomes crucible 2
When the iron-based metal penetrates into the above-mentioned iron-based metal on the inside 3, the iron-based metal is heated and melted by Joule heat generated by a skin current induced on the surface. An induced current flows through the molten metal M of the iron-based metal induced by the coil 14 and a repulsive force generated between these currents
As shown in FIGS. 1 and 3, the molten metal M is formed on the inner side 5 of the side wall 4 by the
And rises upward to be in a semi-floating state.

At this time, the molten metal M is deposited on the side wall 4 of the crucible 2.
1 and 3 by being cooled in contact with
As shown in the figure, a solidified shell S having a height h of several tens of mm solidified in a ring shape is formed below the inner side surface 5 of the side wall 4. However, at the contact surface between the molten metal M and the ceramic 8 at the bottom, the molten metal M is not cooled much, so that the solidified shell S is not formed, and the heat removal through the contact surface is suppressed. That is, since the contact area between the molten metal M and the crucible 2 is significantly reduced as compared with the conventional melting apparatus 20 shown in FIG. 4, the heat removal from the molten metal M can be reduced.

The temperature of the molten metal M is such that the heat input to the molten metal M generated by the power supplied from the power supply 16 to the high frequency induction coil 14 and the heat removal from the molten metal M to the crucible 2 are balanced. Determined by the state. That is, when the heat input increases, the rising of the molten metal M in the crucible 2 increases, so that the contact area with the side wall 4 of the crucible 2 increases and the solidified shell S increases, so that the heat removal also increases. On the other hand, when the heat input is reduced, the rising of the molten metal M in the crucible 2 is reduced, so that the contact area with the side wall 4 of the crucible 2 is reduced and the solidified shell S is reduced, so that the heat removal is also reduced. For this reason, once the iron-based metal is melted, the temperature of the molten metal M can be kept constant while the heat input and the heat removal are equilibrated at a relatively low level. Using the molten metal M maintained at a constant temperature with such a small input power, the ceramic mold 4 is resistant to gravity.
By casting the molten metal M into the metal mold 0, it is possible to reliably and efficiently manufacture a low-cost, high-precision precision casting product.

Therefore, as shown in FIG.
To increase or decrease the input power from the power supply 16 and increase or decrease the heat input supplied to the molten metal M from the high-frequency induction coil 14, thereby increasing the molten metal M and the side wall 4 of the crucible 2.
By changing the contact area with the molten metal M and changing the height h of the solidified shell S, the heat removal from the molten metal M can be increased or decreased. For this reason, for example, by operating the control means 18 which is integral with the power supply 16 and an accessory thereof, the heat input to the molten metal M can be increased or decreased. Alternatively, based on the heat input and heat removal measured in advance, in order to bring the heat input and heat removal into an equilibrium state at a lower level in the shortest time, the control unit 18 as a computer derives it by a required program. The power supplied to the power supply 16 can be increased or decreased according to the optimum increase / decrease pattern. In the latter case, the molten metal M once obtained by melting is
Since the equilibrium state between heat input and heat removal at a desired low level can be almost automatically achieved, the casting operation described below can be performed stably and reliably.

That is, as shown in FIG.
Argon gas is filled in the inside 34 of the suction hole 3
When the chamber 35 is degassed and depressurized, the molten metal M in a semi-floating state in the crucible 2 becomes:
It rises through the nozzle 29 against the gravity, and is cast into the cavities C1, C2,... Of each product section 48 through the runner 46 of the ceramic mold 40. When the pressure in the chamber 35 is restored to the atmospheric pressure approximately several minutes later, the molten metal in the runner 46 falls into the crucible 2 through the nozzle 29. Then, by opening the lid plate 38 and separating the removed mold 40,
A precision cast product of an iron-based metal having a shape following the cavities C1 and C2 is obtained.

When the ferrous metal is melted before casting the ferrous metal, a crucible made entirely of ceramic is generally used. In addition, it is necessary to prevent the components from coming off due to the residue, and the life of the crucible is limited to several tens of heat at the longest. For this reason, there is also a problem that the cost of the ceramic crucible increases. On the other hand, in the melting apparatus 1, the copper crucible 2 used for melting has a lifetime of several hundred thousand heats, which is almost semi-permanent, so that melting and casting can be performed at extremely low cost. Moreover, even if the metal is changed to a metal having a different composition, the inner surface 5 of the crucible 2 is tapered, so that the remaining solidified shell S can be easily removed.
There is also an advantage that the subsequent dissolution can be performed without contamination. Therefore, it is possible to provide a high quality cast product with high accuracy and at low cost.

[0025]

In the following, specific examples of the present invention are described.
A description will be given in conjunction with a comparative example. Stainless steel (SUS30
4: Iron-based metal) 3 sets of 50 kg were prepared. The inside diameter of the bottom of the inside 3 is 200 mm, and the inside height of the side wall 4 is 240 mm
A copper crucible 2 having a diameter of 200 mm and a thickness of 40 mm disposed at the bottom of the inside 3, a copper crucible 2, comprising a water-cooled segment 4 a having a taper of 2 degrees on the inner surface 5. FIG. 3 including
Was prepared. Also, inside 2
3 has an inner diameter of 200 mm and an inner height of the vertical side wall 24 of 2
The melting device 20 of Comparative Example 1 shown in FIG. 4 including the copper crucible 22 of 40 mm was prepared. Furthermore, if the inside diameter of the furnace is 2
Comparative Example 2 in which a high-frequency induction coil was wound around a ceramic crucible having a height of 00 mm and a height of 220 mm
Of an induction furnace was prepared.

In the melting apparatus 1 of the embodiment and the melting apparatus 20 of the comparative example 1, the guide 30, the chamber 35 and the ceramic mold 40 shown in FIGS.
Was set above. For the induction furnace of Comparative Example 2, the same ceramic mold 40 was prepared and its runner 4 was used.
6 was turned upside down and almost in the shape of a person, so that it was overpoured. Inside the copper crucibles 2 and 22 of Example and Comparative Example 1 or Comparative Example 2
After individually loading the 50 kg of stainless steel into the ceramic crucible described above, the stainless steel was induction heated and melted by energizing the high frequency induction coils 14, 28 and the like. Of these, in the melting apparatus 1 of the embodiment, the output from the power supply 16 is adjusted by the control means 18 so that the heat input and the heat removal of the molten stainless steel (molten metal) M are appropriately balanced at a low level. Operated.

Next, the inside 34 of the guide 30 is filled with argon gas in advance, and the inside of the chamber 35 is depressurized by evacuating from the suction hole 39 to reduce the pressure inside the chamber 35.
A vacuum suction casting is performed in which the melted stainless steel M inside the nozzle 22 is lifted up in the nozzle 29 against gravity and cast into the cavities C1, C2,. Anti-gravity casting) was performed to obtain a predetermined cast product. In the dissolving apparatuses 1 and 20 of Example and Comparative Example 1,
The above-mentioned casting operation was performed several times. On the other hand, all of the melted stainless steel M in the ceramic crucible of Comparative Example 2 was cast sequentially into the plurality of ceramic molds 40 in the over-poured state by tilting the induction furnace to obtain a cast product similar to the above. I got Power output in each of the above examples,
The frequency of the current, the molten metal holding power when the molten stainless steel M is maintained at a certain temperature, and the molten stainless steel M
Table 1 shows the heat input efficiency of the molten metal, which is the ratio of the energy input to the heater to the input power.

In Examples and Comparative Examples 1 and 2, the retained energy balance when the molten stainless steel M was maintained at a constant temperature was obtained by measuring the heat input and the heat removal. The heat is removed from the free surface radiated to the space from the molten stainless steel M in each example, and from the molten metal contact surface between the molten stainless steel M and the copper crucible 2, 22 or the ceramic crucible in each example. It was measured separately from heat removal. These results are also shown in Table 1. Furthermore, in the casting operation in Examples and Comparative Examples 1 and 2, the cycle time of the casting operation, the yield of the obtained cast product, and the power consumption per unit of the cast product for each example were measured or calculated. These are also shown in Table 1.

[0029]

[Table 1]

According to Table 1, in the embodiment and the comparative example 1 in which the same antigravity casting was performed, the embodiment required less power or frequency in the power supply output, the current frequency, and the molten metal holding power than the comparative example 1. Moreover, the heat input efficiency of the molten metal was slightly higher than that of Comparative Example 1. This is based on the fact that in the embodiment, the output of the power supply 16 was adjusted by the control means 18 described above, and the operation was performed so as to balance the heat input and the heat removal of the molten stainless steel (molten metal) M at a low level. Further, the relationship between the retained energy balance of the example and the comparative example 1 is also based on the same reason. In Comparative Example 2, as shown in Table 1, the electric power or the like was low or the highest heat input efficiency of the molten metal was exhibited in the above items as a whole, but this was caused by using an induction furnace including a normal ceramic crucible. However, the heat input of the retained energy balance was the lowest.

Further, as shown in Table 1, the embodiment and the comparative example 1 were arranged in the same casting cycle time and the same casting yield, but in terms of electric power consumption, the example was the comparative example 1.
It became half. This is also attributable to the operation in the embodiment to balance the above-mentioned heat input and heat removal at a low level. On the other hand, in Comparative Example 2, the casting cycle time was the longest and the casting yield was as low as 30% due to the casting of the upper pouring type, so that the power consumption was the highest. From the above results, it can be seen that the advantages of the metal melting method and the melting apparatus 1 of the present invention applied to the examples can be easily confirmed, and that the effects of the present invention are also sufficiently supported.

The present invention is not limited to the embodiments and examples described above. For example, the material of the crucible of the melting device is not limited to the pure copper, and other metals or alloys having the same heat conductivity and heat resistance can be applied to other copper alloys rather than the base. . Further, using the guide 30, the chamber 35 whose inside is evacuated, and the ceramic mold 40, antigravity casting can be performed on the molten metal M in the copper crucible 2 by pressurization with an inert gas. Alternatively, the pressure of the inert gas inside the crucible 2 where the molten metal M is located is increased by using the chamber 35 and the ceramic mold 40 filled with a low-pressure inert gas therein, and the inside 3 and the ceramic mold 40 are increased. The anti-gravity casting can also be performed by the pressure difference between. Further, the taper applied to the inner surface of the crucible can be appropriately selected within a range of 0.5 to 10 degrees. The dissolution method and dissolution apparatus of the present invention include:
Not only iron-based metals, but also other metals and alloys other than high-melting-point active metals such as titanium can be applied.

[0033]

The metal melting method of the present invention described above.
According to the first aspect of the present invention, the bottom of the crucible is formed of a heat insulating ceramic so that heat extraction from the molten metal can be suppressed, and the heat extraction and the heat input by induction heating are balanced at a relatively low level. In this state, the metal can be melted while keeping the temperature of the molten metal constant. Therefore, even for iron-based metals, the cost of power and the resulting manufacturing cost can be reduced, so that it is practical to melt in a semi-floating state and perform antigravity casting. According to the metal melting method of the second aspect, the contact area between the molten metal and the crucible changes, and accordingly, heat removal from the molten metal and heat input required for induction heating are performed at an arbitrarily low level. Since the balance can be ensured, stable semi-floating melting and antigravity casting can be performed while suppressing the power cost.

On the other hand, the metal melting apparatus of the present invention (claim 3)
According to the method, since the bottom of the crucible is formed of a heat insulating ceramic, the heat removal from the molten metal can be suppressed. With the equilibrium at a low level, the temperature of the molten metal can be kept constant to melt the molten metal. Therefore, even if it is an iron-based metal, the power cost and the production cost resulting therefrom can be reduced, so that the melting in a semi-floating state and the antigravity casting can be performed practically. According to the metal melting device of the fourth aspect, the residual metal solidified in the portion where the molten metal and the crucible are in contact with each other can be easily removed from the crucible. The cycle time required for each process can be reduced, and the manufacturing cost can be further reduced. In addition, since the crucible can be prevented from being contaminated, semi-floating melting can be easily performed even when the metal to be melted is replaced with a dissimilar metal. Further, claim 5
According to the metal melting device of the present invention, the crucible can be sealed in an airtight state, so that the holding of the atmospheric gas in the crucible and the evacuation can be facilitated. There is no need to form a vacuum chamber surrounding the entire melting apparatus, including the outer high frequency induction coil.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a main part of a metal melting apparatus according to the present invention.

2A is a perspective view of a crucible used in the melting apparatus of FIG. 1, and FIG. 2B is a cross-sectional view taken along a line BB in FIG.

FIG. 3 is a schematic view showing a metal melting apparatus according to the present invention.

FIG. 4 is a schematic view showing a conventional metal melting apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Metal melting apparatus 2 ... Crucible 4 ... Side wall 4a ... Water cooling segment 5 ... Inner surface 8 ... Ceramic 12 ... Airtight seal 14 ... High frequency induction coil 16 ... Power supply 18 ... Control means 40 ... Ceramic mold (mold) ) M: Stainless steel (metal, molten metal)

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) F27D 11/06 F27D 11/06 A H05B 6/26 H05B 6/26 6/32 6/32 F term (reference) 3K059 AB09 AB16 AB20 AB27 AB28 AC33 4K001 AA10 BA23 FA14 GA17 GB11 4K046 AA01 BA01 BA02 CA01 CB06 CB15 CD02 CE01 CE03 DA05 EA02 EA03 4K051 AA06 AB03 HA18 4K063 AA04 AA12 BA02 BA03 CA01 FA03 FA07

Claims (5)

[Claims] 1. A method in which a metal charged in a crucible is induction-heated and a molten metal is cast into a mold above the crucible against gravity, and the side wall of the crucible is made of copper or the like. A method for melting a metal comprising a water-cooled segment and using a melting device in which the bottom in the crucible is made of ceramic, wherein the molten metal charged in the crucible and induction-heated is levitated by electromagnetic induction repulsion and The lower side surface of the molten metal is brought into contact with the water-cooled segment of the crucible side wall, and by balancing the heat removal by the contact and the heat input by the induction heating, the metal while keeping the temperature of the molten metal constant Dissolving a metal. 2. The floating state of the molten metal is changed by controlling the input power required for the induction heating to increase or decrease the heat input in order to balance the heat removal and the heat input at an arbitrary level. The method according to claim 1, wherein the heat removal is increased or decreased by changing a contact area between the molten metal and a side wall of the crucible. 3. A crucible including a side wall made of a water-cooled segment made of electrically insulated copper or the like and a bottom part made of ceramic; a high-frequency induction coil wound around the crucible at an interval; A metal melting device, comprising: a power supply for supplying power to the high-frequency induction coil from the power supply; and a mold positioned above the crucible. 4. The melting of a metal according to claim 3, wherein an inner surface of the water-cooled segment forming the side wall of the crucible facing the inside of the crucible is tapered so as to expand upward. apparatus. 5. The metal melting apparatus according to claim 3, wherein an airtight seal is arranged along an outer periphery of a water cooling segment forming a side wall of the crucible.