JPH11273850A - Flotation melting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase productivity by shortening the cycle time of melting and tapping work for a flotation melting device. SOLUTION: A changeover device 9 is provided for changing over an electrical path coming from an alternating-current power supply 3 from one flotation melting device to another, melting preparations for one flotation melting device are made during the melting and tapping period of another flotation melting device connected to the alternating-current power supply 3, and after the tapping of this flotation melting device has been completed, the electrical path is switched to that flotation melting device, so that it can perform melting, thus the intervals of melting/tapping work are shortened, whereby productivity is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flotation and melting apparatus for improving the productivity of an apparatus for melting and melting a metal to be melted in a crucible.

[0002]

2. Description of the Related Art In a levitation melting apparatus, an induction current is generated between a molten metal in a crucible and a crucible made of a good conductive metal by an induction coil wound on the outer peripheral side of the crucible, and the induced currents of the molten metal and the crucible are opposed to each other. Since the reciprocal directions are opposite to each other, an electromagnetic repulsive force is generated, and the repulsive force floats the molten metal so that the crucible and the molten metal can be melted in a non-contact state.

[0003] In this apparatus, the molten metal is always kept in a floating state, so that the molten metal can be obtained with high purity without mixing of impurities from the crucible. By pouring this molten metal into a mold, it is possible to produce a high-purity cast product, for example, an active metal such as titanium, a high-melting-point metal (chromium, niobium,
Suitable for dissolving molybdenum), silicon, etc. Since the electromagnetic force acting on the crucible is strong, the molten metal is electromagnetically stirred, and is suitable for alloy melting in which a uniform structure is required.

FIG. 2 shows the structure of a conventional levitation melting apparatus.
(A) shows a phase diagram during melting, and (b) shows a phase diagram during tapping. In FIG. 2, reference numeral 1 denotes a crucible formed by arranging two or more electrically insulated segments in the circumferential direction with an insulator interposed therebetween and forming an outlet 1a at the bottom. The inside of the crucible 1 is hollowed out, and the metal to be melted is put in this portion. An induction coil 2 is provided on the outer peripheral side of the crucible 1.
Is wound, and the crucible 1 and the induction coil 2 constitute a levitation melting furnace, to which an AC power supply 3 is added to form a levitation melting apparatus. In addition, when a high-frequency current is not supplied from the AC power supply 3 to the induction coil 2 due to a power failure during melting or other accidents, the bleeding force to the molten metal is lost and the molten metal flows out of the outlet 1a. A plug 4 for preventing the device from dropping from and damaging the device below is detachably mounted by a plug opening / closing mechanism (not shown).

A magnetic flux generated by supplying a high-frequency current from the AC power supply 3 to the induction coil 2 links the segments to induce eddy currents, and a magnetic space formed by an insulator between the segments. (Referred to as a slit) to enter the inside of the crucible through the crucible and interlink with the metal to be melted in the crucible to induce an eddy current in the metal to be melted. Since the directions of the eddy currents induced in the segment and the metal to be melted are opposite to each other on the opposing surfaces, magnetic repulsion is generated. Since the crucible 1 is fixed, a floating force acts on the metal to be melted, and If the force is greater than the weight of the molten metal, the molten metal floats away from the crucible 1. The metal to be melted continues to be heated due to the resistance loss due to the eddy current. Therefore, the metal to be melted is dissolved in a floating state.

Although there are various methods for taking out the molten metal melted by the flotation melting apparatus, an outlet 1 a is provided at the bottom of the crucible 1.
There is a method of continuously or intermittently taking out the molten metal from the outlet 1a (see Japanese Patent Application Laid-Open No. 5-195050). According to this publication, while melting the metal in the crucible 1 while controlling the current of the induction coil to be substantially constant,
A small piece of the solid material is continuously or intermittently supplied from the upper portion of the crucible, and the molten metal corresponding to the supply amount is continuously or intermittently discharged from the outlet 1a, taken out, and then poured into a mold. . According to Japanese Patent Application Laid-Open No. Hei 7-245182, the outlet 1a is closed using the plug 4 and the tap 4 is opened at the time of tapping so that the timing and amount of tapping can be freely controlled.

According to this, the molten metal is in a floating state irrespective of the presence or absence of the plug, and at the time of tapping, the electromagnetic force is weakened by adjusting the current of the induction coil, so that the tapping can be performed from the outlet 1a. In addition, at the time of tapping, since hot water and the outlet 1a exert repulsive forces on each other, the tapping can be performed in a non-contact manner. Therefore, if the metal that has been floated and melted is tapped in this manner, it can be melted and tapped without contact. In this method, after the metal to be melted is completely melted (see FIG. 2 (a)), the tap 4 is opened to start tapping (see FIG. 2 (b)). Continuous operation is performed by repeating the process of closing the stopper 4 and adding and dissolving the material.

[0008]

In the conventional configuration in which a levitation melting furnace and an AC power supply are paired, preheating of the crucible is not required as compared with the case of melting with a crucible made of refractory. Rapid melting and tapping are possible, and it is possible to perform from melting to tapping in a short time. For example, in a 50 kg flotation melting apparatus, 50 kg of iron is completely melted in about 5 minutes starting from a cold material, and the tap water can be completely drained in about 15 seconds when flowing from an outlet. But,
To move to the next dissolution, removal of residues such as slag in the crucible and cleaning work are interposed, and during these times (15 to 30).
Since the production was interrupted during the period, it was difficult to continuously produce a large number of castings.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a flotation melting apparatus in which the cycle time of melting and tapping is shortened to improve productivity. It is in.

[0010]

In order to solve the above-mentioned problems, the invention according to claim 1 is an invention which is formed in a cylindrical shape having a bottom and has an outlet for discharging molten metal at the bottom thereof, and a radially substantially cylindrical shape at the cylindrical portion. A crucible made of a good conductive metal having vertically elongated slits provided at intervals, a plurality of levitation melting furnaces having an induction coil wound around the outer diameter side of the crucible, and an AC power supply for supplying a high-frequency current to the levitation melting furnace And a switching device for switching an electric circuit from the AC power supply to one of a plurality of flotation melting furnaces.

According to the above configuration, while the melting and tapping operation is performed by the flotation furnace connected to the AC power supply, the molten material is set in another flotation furnace not connected to the AC power supply and connected to the AC power supply. As soon as the melting and tapping operation of the floating melting furnace is completed, the AC power source is switched to another floating melting furnace in which the molten material is set and the melting operation is shifted to the melting operation. In addition to performing internal cleaning work, setting the melting material and preparing for the next melting, melting and tapping work can be performed continuously by switching one AC power supply to multiple floating melting furnaces This makes it possible to shorten the cycle time of dissolution.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a configuration diagram of a main part of an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a crucible formed by arranging two or more electrically insulated segments in the circumferential direction with an insulator interposed therebetween and forming an outflow port 1a at the bottom. The inside of the crucible 1 is hollowed out, and the metal to be melted is put in this portion. An induction coil 2 is wound around the outer periphery of the crucible 1, and a high-frequency current is supplied from an AC power supply 3. In addition, when the high frequency current is no longer supplied from the AC power supply 3 to the induction coil 2 due to a power failure during melting and other accidents, the bleeding force to the molten metal is lost and the molten metal is discharged from the outlet 1a. A plug 4 for preventing the device from dropping from and damaging the device below is detachably mounted by a plug opening / closing mechanism (not shown). 6 is an N composed of a crucible 1 and an induction coil 2
o. 1 is a flotation melting furnace, and 7 and 8 are similarly configured N
o. 2, No. 3 levitation melting furnace. No. 9 is the aforementioned No. 1
-No. 3 is a switching device for switching and connecting the flotation melting furnace and the AC power supply 3, and the A1, B1 group, A2, B
It is configured so that one can be switched to three places of two loops, A3 and B3 groups. In FIG. 1 The levitation melting furnace 6 is connected to the AC power supply 3 via the A1 and B1 terminals of the switching device 9, and the AC power supply 3
The work until the molten metal 5 in the crucible 1 is melted by the high-frequency current supplied to the crucible 1 and the molten metal 5 is floated is discharged. The stopper 4 is attached to the outlet 1a.

No. 2, No. 3 The flotation furnaces 7, 8
Although connected to the A2, B2 terminals and A3, B3 terminals of the switching device 9, respectively, they are disconnected from the AC power supply 3 and cannot be energized. And No. No. 2 flotation melting furnace 7 has already set the metal to be melted in the furnace. (1) As soon as the flotation melting furnace 6 completes melting and tapping work, the switching device 9
No. 2, switching to B2 terminal, waiting to start melting and tapping work. 3 The levitation melting furnace 8 has just opened the tap 4 attached to the outflow port 1a and finished the tapping operation, and is trying to remove slag and the like and prepare the furnace for the next melting. It is in the state that it is. In this way, No. 1 to No. By sequentially switching and using the three floating melting furnaces 6, 7, and 8, the cycle time of melting can be shortened as a whole, and the productivity can be improved.

The molten metal 5 to be melted and discharged in this way is supplied to a mold set below each of the flotation melting furnaces 6, 7, 8 in accordance with the casting amount such as intermittent or full-volume tapping. It can be cast into a cast product, or can be cast into a cast rod by performing continuous casting while introducing molten metal. Further, in this embodiment, the case where the number of the levitation melting furnaces is three is described, but any two or more levitation melting furnaces may be used.

[0015]

According to the present invention, continuous operation becomes possible by switching a plurality of crucibles to melting and tapping operations. Therefore, since the downtime of the apparatus itself is reduced, it is possible to continuously produce a cast product, and it is possible to increase the production amount per hour, reduce the running cost, and improve the production efficiency. In addition, the amount of hot water from one furnace is intermittent hot water, in which the entire amount of hot water is supplied, the current to the induction coil is controlled during hot water supply to interrupt the hot water supply, or the current to the induction coil is controlled again to restart hot water supply. Since various tappings such as tapping while supplying molten metal can be handled, operation not affected by the molten material and the casting weight per frame is possible. In addition, even when dissolving or tapping different kinds of metals, the crucible does not get wet with the metal just melted, so just removing the slag etc. prepares for the next melting and tapping, and mixes different metals with the change of denomination It is possible to operate continuously without the need to stop the operation for the operation of removing the water.

In addition, since most of the equipment cost in the flotation melting apparatus is occupied by the AC power source, improving the productivity by effectively using the AC power source results in a reduction in the cost amortization cost included in the product cost. effective.

[Brief description of the drawings]

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

FIGS. 2A and 2B show a configuration of a conventional flotation melting apparatus, wherein FIG. 2A is a state diagram during melting, and FIG.

[Explanation of symbols]

 1 Crucible 1a Outflow port 2 Induction coil 3 AC power supply 4 Plug 5 Melt 6 No. 1 flotation melting furnace 7 No. 2 Floating melting furnace 8 No. 3 Floating melting furnace 9 Switching device

Claims (1)

[Claims] 1. A crucible made of a good conductive metal having an outlet formed in a cylindrical shape with a bottom and discharging molten metal at the bottom thereof, and vertically elongated slits radially provided in the cylindrical portion at substantially equal intervals.
And a plurality of levitation melting furnaces in which an induction coil is wound on the outer diameter side of the crucible; an AC power supply for supplying a high-frequency current to the levitation melting furnace; and an electric path from the AC power supply to a plurality of levitation melting furnaces. A levitation and melting device, comprising: a switching device for switching between the two.