JP2003307390A - Cold crucible melting casting apparatus and melting casting method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To enable stable and continuous production of ingots for cold crucible melting and casting equipment not only for volume reduction of molten materials but also for recycling of used materials and production equipment. To A crucible providing a desired melting capacity and an induction coil are extended to a height at which only a crucible height or a substantially entire amount of a melting material equivalent to a crucible volume can be set in a crucible from an initial stage of melting. The induction coil 11 dissolves the molten material in the opposing portion and moves the relative position from the lower portion to the upper portion of the crucible side wall while melting the solid material on the upper part of the melt into the lower melt.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold crucible melting casting apparatus for manufacturing an ingot by exciting an induction coil by using a high frequency power source and induction heating melting casting of a molten material in a water-cooled metal crucible, and a melting casting method thereof. Regarding

[0002]

2. Description of the Related Art A cold crucible melting device is a device in which an induction coil is wound around a water-cooled metal crucible. When a melting material is put inside a metal crucible and a high-frequency current is passed through the induction coil, an eddy current is induced in the melting material, and the melting material is heated and melted. The melted material melted by this method does not contain impurities from the crucible, so that a high-purity melt can be obtained.

By casting this molten metal, a high-purity cast product can be produced, which is suitable for melting active metals such as titanium and refractory metals (chromium, niobium, molybdenum). Further, since the electromagnetic force acting on the molten metal is strong, the molten metal is electromagnetically stirred and is suitable for alloy melting which requires a uniform composition. FIG. 7 shows a configuration diagram of a conventional example. In FIG. 7, the cold crucible melting and casting apparatus is
Circularly wound induction coil 2 connected to one power supply 5
A water-cooled metal crucible 1 having two or more electrically insulated segments arranged side by side in the circumferential direction of the induction coil 2 through a slit is skirted inside. A material supply device 6 is provided above the water-cooled metal crucible 1, and a pull-out drive device 7 that can be separated from the water-cooled metal crucible 1 is provided at the bottom of the water-cooled metal crucible 1. In the case of this example, the water-cooled metal crucible 1, the induction coil 2, and the drawing drive device 7 have a vacuum exhaust system for atmosphere control, a gas supply system, etc. which are not described in order to enable melt casting under controlled atmosphere. It is installed in the vacuum container 9. High frequency power 5
To the induction coil 2 via a coaxial feeder 5a configured to maintain a vacuum atmosphere.

Further, the material supply device 6 has a hopper 6a for storing the melted material, an electromagnetic feeder 6b for cutting out the melted material from the hopper 6a, a shutter valve 6c for guiding the cut out melted material into the vacuum container 9, and a shutter valve 6c. And a shooter 6d for supplying the molten material to the water-cooled metal crucible 1, and the atmosphere in the vacuum vessel 9 is maintained by closing the shutter valve 6c.

In the structure of the bottom of the crucible which can be separated from the water-cooled metal crucible 1, a water-cooled metal plate or a plate material of the same material as the melting material called a starting block 4 is connected to the drawing drive device 7. Further, the pull-out driving device 7 receives the ingot 8 obtained by solidifying the molten metal 3 in the lower part of the water-cooled metal crucible 1, and a receiving device that is directly connected to the water-cooling metal plate and can move up and down along guide shafts on both sides. A motor case 7a which houses a movable part composed of a base and a motor 7c for driving the movable part, and also serves as a base for supporting the guide shaft and the movable part.
And a transfer device 7c configured to laterally move the motor case 7a and move the ingot 8 from immediately below the water-cooled metal crucible 1 to take it out.

In order to manufacture the ingot 8 by using this apparatus, first, the molten material as a raw material is in a solid state from the hopper 6a of the material supply apparatus 6 through the electromagnetic feeder 6b, the shutter valve 6c, and the shooter 6d. Add to crucible 1 from above. Next, when a high-frequency current is passed through the induction coil 2, the introduced raw material is melted by induction heating in the crucible to form a molten metal 3. The molten metal 3 is first cooled by the water-cooled metal plate of the drawing drive device and solidified on the water-cooled metal plate. By driving the motor 7c in the motor case 7a while additionally supplying the melted material from the upper part of the water-cooled metal crucible 1 in order to draw the molten metal 3 from the bottom of the crucible, the moving part of the drawing drive device 7 is guided along the guide shaft. When the molten metal 3 is gradually moved downward by cooling, the molten metal 3 is cooled by a cooling unit provided in the lower portion of the water-cooled metal crucible 1 and is pseudo-solidified to form solidified metal on the water-cooled metal plate to form an ingot. ,
The water-cooled metal crucible 1 is connected to the lowering of the drawing drive device 7.
Is continuously drawn downward from the bottom of the.

This method is capable of continuously melting and casting the melted material, and when compared with the conventional transfer type plasma arc melting method, the cost of manufacturing the consumable electrode with the melted raw material can be saved. It is suitable for mass-producing inexpensive products such as titanium and titanium alloys. The current of the induction coil 2 supplied from the high-frequency power source 5 induces an eddy current in each segment electrically insulated by the slit, and also induces an eddy current in the metal as the melting material and the molten metal 3. Since the directions of the eddy currents flowing in the water-cooled metal crucible 1 and the molten metal 3 are opposite to each other on the facing surfaces, magnetically repulsive force is exerted, and the water-cooled metal crucible 1
Is fixed, the molten metal 3 is separated from the side wall of the water-cooled metal crucible 1 if the repulsive force acting on the molten metal 3 is larger than the weight of the molten metal 3. The molten metal 3 generates heat due to resistance loss and keeps heating. For this reason, the melt 3 has a lower portion σh below the position where the static pressure of the melt and the electromagnetic repulsive force are balanced on the side of the crucible where the bottom of the crucible contacts
In> F, it melts in contact with the water-cooled metal crucible 1.

Here, σ: weight per unit surface area of the molten material [kg / m ³ ] h: molten metal head (height from the upper surface) [m] F: electromagnetic repulsion force per unit area acting on the molten metal [ kg/
m ² ].

The above-mentioned cold crucible induction heating melting method is used for melting active metals as mentioned above, since impurities are not mixed from the crucible material.

[0010]

By the way, in the melting of metal by induction heating using a cold crucible, the melting efficiency and the heating efficiency of the metal vary depending on the position of the molten metal with respect to the position of the induction coil (that is, the molten metal position), Since there is an optimum molten metal surface position, control of the molten metal surface position is important. In order to control the molten metal surface position, various methods of measuring the molten metal surface position such as eddy current sensor system, video camera system, laser distance meter system, magnetic flux density detection system have been studied so far. It was difficult to detect the position, which is possible, highly accurate, and easy to automate. When actually operating using this device, in addition to the optimization control of the induction coil position and the molten metal position, the actual input amount control from the material supply device and the pulling drive amount control from the pulling drive device, It is necessary to optimize the control of each mechanism such as the operating power of the high frequency power source, and it is considered that the above problem exists in the case of producing stable and continuous ingots for production equipment.

The present invention has been made to solve the above problems associated with the operation of a cold crucible melting and casting apparatus using a conventional continuous casting apparatus.
Without using a material feeder at the time of ingot production,
By manufacturing the ingot by adjusting the operating power of the high-frequency power source and raising the induction coil or lowering the water-cooled metal crucible, not only volume reduction processing of the molten material but also recycling of used materials and stable production equipment can be achieved. It is an object of the present invention to provide a cold crucible melting and casting apparatus for continuously producing ingots and a melting and casting method performed using the apparatus.

[0012]

As a result of confirming the melting portion temperature with respect to the relative position between the position of the molten metal in the crucible and the position of the induction coil, the inventor has found that the position of the upper surface of the molten metal is 0 to 0 from the upper end of the induction coil. It has been confirmed that the highest position of the melting portion temperature exists near the upper side of 20 mm.

This indicates that the optimum position of the melting efficiency in the relative position between the molten metal surface position in the crucible and the induction coil position is that the upper surface position of the molten metal is near 0 to 20 mm above the upper end of the induction coil. There is. When manufacturing ingots using the cold crucible melting and casting equipment,
The material supply from the material supply device and the lower withdrawal drive of the water-cooled metal crucible from the withdrawal drive device are performed while maintaining the above positional relationship with respect to the relative position between the molten metal surface position and the induction coil position. The above relative positional relationship is a condition for a free surface where there is no solid material of molten metal at the top of the molten metal, but if there is a molten material in the solid state above the molten metal in the previous relative positional relationship, induction will occur when the material is melted. When operated and maintained at the same amount of electric power as or more than the amount of electric power input to the coil, the molten metal above the molten metal melts by melting into the molten metal that has already melted up to around the upper end of the induction coil. The inventor has confirmed that this has been done.

This is because when a solid material is present above the melt, the melt is closer to the induction coil than the solid material,
Since a large induction current flows due to the molten metal that has melted into a lump, most of the electric power input from the induction coil is input to the molten metal that has already melted, so the molten metal is kept in the molten state and It is considered that it is possible to heat and melt the solid material by radiant heat of the molten metal and induction heating from the induction coil. By holding the same power as the power actually applied to the induction coil (in some cases, the power equivalent to the melting energy of the solid material corresponding to the surface facing the induction coil is added), the surface facing the induction coil It is possible to melt the solid material above one melt into the melt below.

The present invention is based on this finding,
In order to solve the above-mentioned problems, the invention of claim 1 is a cold crucible melting and casting apparatus which excites an induction coil by using a high frequency power source to induction-melt the melting material in a cylindrical water-cooled metal crucible. The vertical length of the induction coil is longer than the vertical length of the induction coil, and there is an induction coil driving means capable of moving the induction coil in the vertical direction or a water cooling metal crucible driving means capable of moving the water cooling metal crucible in the vertical direction. However, the relative position of the induction coil and the water-cooled metal crucible is moved.

According to the invention of claim 2, in the cold crucible melting and casting apparatus according to claim 1, there is provided a lower water-cooling metal crucible which is separable and has a bottom inner surface having a conical shape or a bowl shape in the lower part of the water-cooling metal crucible. Is characterized by. Further, the invention of claim 3 is a cold crucible melting casting method for exciting a melting material in a cylindrical water-cooled metal crucible by induction heating using a high frequency power source to melt the melting material in an amount corresponding to the crucible capacity. It is placed in a water-cooled metal crucible, and molten metal is formed at the bottom of the water-cooled metal crucible at the beginning of melting to serve as the initial seed material, and either the induction coil is raised or the water-cooled metal crucible is lowered to cause the induction coil and the water-cooled metal crucible. The cold crucible melting is characterized in that the ingot is manufactured by moving the relative position of the upper part to the upper part, melting the molten material in the upper part of the molten metal while melting it in the seed material, and casting the lower part of the molten metal in a water-cooled metal crucible to solidify it. The casting method is used.

According to the inventions of claims 1 to 3,
Since all the melting material is set in the crucible at the beginning of melting,
It is not necessary to control the amount of melted material input during melting, and at the beginning of melting, molten metal is formed at the bottom of the crucible and the molten metal is used as the initial seed material to raise the induction coil or drive the entire water-cooled crucible down. As a result, it is possible to manufacture an ingot by melting and melting the molten material corresponding to the induction coil facing portion in the upper part of the crucible into the seed water material in the lower part of the crucible, and casting and solidifying in the water-cooled metal crucible in the lower part of the crucible.

Further, as already described, when the solid material is present in the upper part of the molten metal, most of the electric power supplied from the induction coil is supplied to the molten metal which has already been melted, so that the molten metal is kept in a molten state. On the other hand, the solid material in the upper part of the molten metal can be heated and melted by radiant heat of the molten metal and induction heating from the induction coil. By holding the same power as the power actually applied to the induction coil (in some cases, the power corresponding to the melting energy of the solid material corresponding to the coil facing surface is added), the power is applied to the induction coil facing surface. It is possible to melt the solid material in the upper part of the molten metal into the molten metal below it, and raise the induction coil so as to be able to hold the electric power, or lower the water-cooled metal crucible to achieve good melting efficiency, and Casting becomes possible.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing the main part of an embodiment of the present invention. Further, FIG. 2 is a state diagram in the initial stage of melting of the configuration of FIG. 1, FIG. 3 is a configuration diagram of an example of moving the induction coil in FIG. 1, and FIG. 4 is a diagram of an example of moving the water-cooled metal crucible up and down in FIG. A block diagram is shown. Further, FIG. 5 is a block diagram of an apparatus for carrying out the ingot melted and solidified in FIGS. 1 to 4 just below the crucible. 1, FIG. 2, FIG. 3, FIG. 4, and FIG. 5, members given the same reference numerals as those in the conventional example have approximately the same function, and therefore the description thereof will be omitted.
1, FIG. 2, FIG. 3, FIG. 4, and FIG. 5, the cold crucible melting and casting apparatus is electrically insulated from the inside of the circularly wound induction coil 11 connected to one power source 5. A cylindrical water-cooled metal crucible 1 in which two or more segments are arranged in the circumferential direction of the induction coil 11 via slits.
0 is skirted. Here, the vertical length of the water-cooled metal crucible 10 is sufficiently longer than the vertical length of the induction coil 11 as shown in the figure. Water-cooled metal crucible 1
A material supply device 6 is provided at the upper part of the 0, and a water-cooled metal crucible 10 is provided at the bottom with a pull-out drive device 7 that can be separated from the water-cooled metal crucible 10.

The water-cooled metal crucible 10 serves both as a melting crucible and a casting mold. In order to allow almost all of the solid melting material corresponding to the capacity of the crucible to be charged from the beginning of melting, the water-cooled metal crucible 10 has the same inner diameter as the conventional one. It has a vertically long shape. In the water-cooled metal crucible 10, a melting material as a raw material is set in an amount corresponding to the crucible volume from the beginning of melting.

Here, the capacity of the water-cooled metal crucible 10 is referred to as the weight of the molten metal that can be held in the water-cooled metal crucible 10, and the internal volume is the volume corresponding to the weight of the molten metal and the molten metal above the molten metal. Has a total volume with the volume of the space that does not overflow from the crucible even when agitated. In some cases, a solid material (a plate material or the like) that is the same material as the melting material is used for the starting block 4 so that an eddy current easily flows as a melting start material for the initial melting material.

A water-cooled metal crucible 10 and an induction coil 1 are also provided.
1, the relative position in the vertical direction can be changed. Specifically, an induction coil driving means capable of moving the induction coil 11 up and down with respect to the water-cooled metal crucible 10 is provided, or the induction coil driving means is provided. A water-cooled metal crucible driving means capable of moving the water-cooled metal crucible 10 up and down with respect to the coil 11 is provided.

A method of manufacturing the ingot 8 using this apparatus will be described below. First, the shooter 6d is moved so that its tip is located directly above the water-cooled metal crucible 10, and the molten material in the hopper 6a is charged from the upper part of the water-cooled metal crucible 10 via the electromagnetic feeder 6b and the shooter 6d. At this time, the amount of the melting material charged into the water-cooled metal crucible 10 is set to an amount corresponding to the above-mentioned crucible volume, and when the amount corresponding to the crucible volume is charged into the water-cooled metal crucible 10, the shooter 6d is moved to the initial position ( 1) and retract from the top of the water-cooled metal crucible.

Further, in this initial state, the induction coil 11
Is located at the bottom of the water-cooled metal crucible 10 (see FIG. 1).
reference). The inside of the vacuum container 9 is kept under a reduced pressure atmosphere or a gas atmosphere by a vacuum exhaust system, a gas supply system, etc., which are not shown. Next, when a high-frequency current is applied to the induction coil 11, the melted material that has been introduced is melted by induction heating in the water-cooled metal crucible 10 and the water-cooled metal crucible 1
The molten metal 3 is formed at the relative position of the induction coil 11 in 0, that is, in the bottom of the water-cooled metal crucible 10 in the initial melting state (see FIG. 2).

From the state where the molten metal 3 is used as the initial seed material,
The induction coil 11 is raised by the induction coil driving means to dissolve the undissolved molten material in the initial seed bath material. At this time, the undissolved molten material in the upper portion of the molten metal 3 on the opposite surface of the induction coil 11 can be melted into the molten metal 3 below by radiant heat from the molten metal 3 and induction heating from the induction coil 11. Becomes

On the other hand, the molten metal below the induction coil 11 is
It is cooled and solidified by the water-cooled metal crucible 10 and the water-cooled metal plate of the drawing drive device 7, and the solidified portion is formed from the bottom of the water-cooled metal crucible 10 to manufacture the ingot 8 (FIG. 3).
reference). Here, instead of the method of raising the induction coil 11 by the induction coil driving means, the induction coil 11 is fixed and the entire water-cooled metal crucible 10 is lowered by the water-cooled metal crucible driving means to face the induction coil 11. You may make it raise a surface (refer FIG. 4).

Since it is not necessary to dispose the material supplying device 6 on the upper part of the crucible during the manufacturing of the ingot 8, it is possible to confirm the condition of the device on the video monitor 12 or the like from the upper part of the crucible. If necessary, the rod 13 may be used as the material in the crucible and pushed from above to prevent the hanging material from being generated.

After the molten material is completely melted, as shown in FIG. 5, the water-cooled metal crucible 10 is moved up and down. In the case of FIG. 4, the water-cooled metal crucible 10 is returned to the initial position and fixed by a fixture not shown. Then, after the ingot 8 is pulled out from the bottom of the crucible, it is clamped or chucked by the clamp or chucking device 14, and the ingot transfer device 15 connected to the clamp or chucking device moves it from directly below the crucible and carries it out.

Also, in the case of moving the induction coil in the case of FIG. 3, the drawing drive device 7 is driven to melt the water-cooled metal crucible 1.
After pulling out the ingot 8 solidified in 0 from the bottom of the crucible, it is clamped or chucked by the clamp or chucking device 14 and moved from directly below the crucible by the ingot transfer device 15 connected to the clamp or chucking device 14 to carry it out. .

This device is described as a batch type operation as a basic specification. However, in the case of a device for a large capacity, once the ingot for the capacity of the crucible is manufactured, the material is continuously supplied onto the manufactured ingot and further operated. It is possible to continue operation continuously by restarting. FIG. 6 is a block diagram of the main part of another embodiment of the present invention.

The difference between FIG. 6 and the invention of FIG. 1 is that FIG.
In the invention of FIG. 6, the bottom of the crucible is constituted by a pedestal of the movable part of the pulling drive device, while in the invention of FIG. 6, the bottom of the cylindrical crucible can be separated from the cylindrical crucible and the shape of the inner surface of the bottom is conical. Lower water-cooled metal crucible with a shape or bowl shape 1
0a is provided. Water-cooled metal crucible 10a on the lower part
Since the buoyant force at the bottom of the molten metal 3 is increased by providing the above, the contact area of the molten metal and the water-cooled metal crucible at the initial stage of melting can be reduced, so that the amount of heat removal can be reduced.
It is possible to increase the dissolution efficiency. Other parts of the operation are performed in the same manner as in FIGS.

[0032]

According to the present invention, in a cold crucible melting and casting apparatus, an ingot is adjusted by adjusting the operating power of a high frequency power source and raising an induction coil or driving a water-cooled metal crucible without using a material feeding device during manufacturing of an ingot. For manufacturing, the material is set in the crucible from the beginning of melting to almost the capacity of the crucible. At the beginning of melting, molten metal is formed at the bottom of the crucible, and the molten metal is used as the initial molten material to raise the induction coil. Alternatively, by driving down the entire water-cooled metal crucible, the ingot is manufactured while the unmelted material is being melted into the initial melted material, so that not only the volume reduction of the melted material but also the used material It is possible to produce stable and continuous ingots for recycling and production equipment. In order to monitor the relative position of the induction coil in the crucible and the molten metal surface, which is necessary when operating with the conventional cold crucible continuous casting equipment, in addition to the optimized control of the molten metal position, the actual feeding from the material supply device It is not necessary to perform optimization control among the respective mechanisms such as the amount, the pulling drive amount from the pulling drive device, the operating power control of the high frequency power supply, and the like.

Further, as another effect, unlike the conventional melting and casting apparatus, the material does not drop from the shooter of the material supply apparatus into the molten metal, so that the splash of the molten metal at the time of charging the material is reduced. When the feed material is a cold material, a process of releasing surface deposits or gas by preheating or the like may be required normally, but in the present invention, it is preheated by radiant heat from the molten metal and induction heating in advance of melting. Therefore, even if such work is not performed, it is possible to prevent generation of gas or splash due to a rapid temperature change when the molten material is charged. These are effective in producing ingots without surface defects.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a main part of an embodiment of the present invention.

FIG. 2 is a state diagram in the initial stage of melting of the configuration of FIG.

FIG. 3 is a configuration diagram of an example of moving an induction coil in FIG.

FIG. 4 is a configuration diagram of an example of moving a water-cooled metal crucible up and down in FIG.

FIG. 5 is a configuration diagram of an apparatus for carrying out the ingot melted and solidified in FIGS. 1 to 4 from directly under the crucible.

FIG. 6 is a configuration diagram of a main part of another embodiment of the present invention.

FIG. 7 is a block diagram of a conventional example

[Explanation of symbols]

7c Drawing drive motor 10 Water-cooled metal crucible 11 induction coil 12 video monitor 13 Cue stick 14 Clamp or chucking device 15 Ingot unloading device

Claims (3)

[Claims] 1. An exciting coil is excited by using a high frequency power source,
In a cold crucible melting and casting device that induction-melts molten material in a cylindrical water-cooled metal crucible, the vertical length of the water-cooled metal crucible is made longer than the vertical length of the induction coil, and the induction coil is moved vertically. A cold crucible melting apparatus comprising movable induction coil drive means or water-cooled metal crucible drive means capable of vertically moving a water-cooled metal crucible, and moving relative positions of the induction coil and the water-cooled metal crucible. 2. The cold crucible melting and casting apparatus according to claim 1, wherein a lower water-cooling metal crucible which is separable and has a bottom inner surface having a conical shape or a bowl shape is provided at a lower portion of the water-cooling metal crucible. Casting equipment. 3. An induction coil is excited by using a high frequency power source,
In the cold crucible melting casting method of inductively melting the melting material in the cylindrical water-cooled metal crucible, the melting material equivalent to the crucible volume is charged into the water-cooled metal crucible,
At the beginning of melting, a molten metal is formed at the bottom of the water-cooled metal crucible and used as the initial seed bath material, and either the induction coil is raised or the water-cooled metal crucible is lowered to move the relative position of the induction coil and the water-cooled metal crucible upward. , While melting the melted material on top of the melt into the seed melt,
A cold crucible melting and casting method, characterized in that the lower part of the molten metal is cast and solidified in a water-cooled metal crucible to produce an ingot.