JPS61149783A - Crucible type induction furnace - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to a method for melting metal in a furnace body which is provided with an induction heating filter around the furnace wall in which refractories are stamped and sintered. This type of MIAP1 process for a crucible-type induction furnace that can perform heat treatment can prevent problems such as oxidation of molten metal heated in the furnace body, and also contribute to the production of high-quality metal. A suitable structure is required.

[Prior art and its problems]

Conventional crucible-shaped induction furnaces of this type are generally
As shown in the figure, a heat insulating material 23 is provided along the inside of an induction heating coil 22 formed by winding a conductor having a hollow portion, and is placed on a hearth 26 made of a suitable material. The coil 22 is aligned so that the central axes coincide with each other.
The furnace body 21 is composed of the furnace wall 24a and the furnace bottom 24b, which are solidified by stamping a refractory material between a frame (not shown) for temporary internalization and performing a sintering process. At this time, in order to prevent the magnetic flux due to the magnetomotive force of the induction heating coil 22 from leaking out of the furnace body and passing through the frame and other supporting structures of the furnace body 21, causing heating, the heating coil 22 is An appropriate number of magnetic flux convergence yokes 27 are provided along the outer periphery so that their axes coincide with the axial direction of the furnace body 21, and in order to suppress the temperature rise due to heat loss of the heating coil 22, the conductor is Cooling water is circulated through the hollow part.

In the crucible-shaped induction furnace configured as described above, the metal melted by heat treatment at a predetermined temperature inside the furnace body 21 in the atmosphere under normal pressure is a part of the upper edge of the furnace wall 22. Generally, the molten metal is poured into an appropriate ladle or the like through a pouring hole 25 formed in the molten metal.

However, in this type of crucible induction furnace, as mentioned above,
Since heat treatment of metals, such as melting and heat retention, is generally performed in the open atmosphere, metals that require a dense structure or which are exposed to metallurgically unfavorable phenomena such as oxidation of the molten metal and the contamination of impurities, However, it suffers from the disadvantage that it has an unsuitable configuration for the purpose of producing powder metal.

[Object of the Invention] In view of the metallurgical drawbacks of the conventional crucible-type induction furnace, the present invention requires prevention of oxidation of the metal in the heat-treated furnace body, prevention of contamination of impurities, and a dense structure. An object of the present invention is to provide a crucible-shaped induction furnace that is extremely advantageous for manufacturing metals to be manufactured or powdered metals.

[Key points of the invention]

In order to achieve the above object, the present invention provides the above-mentioned crucible-shaped induction furnace, which includes means for housing the furnace body therein, introducing gas into the interior through the vessel wall, and means for adjusting the pressure of the gas inside. A state in which a nozzle having a nozzle hole that penetrates the bottom of the container and the bottom of the furnace main body and opens into the inside of the furnace main body is provided in the bottom of the closed container, and the closed container is sealed. By providing means for opening and closing the nozzle hole from the top of the container, the metal heat-treated in the furnace body in the atmosphere or in an atmosphere of air or inert gas in the closed container, The pressurized gas introduced into the container via the gas introducing means operates the nozzle hole opening/closing means to pour or inject molten metal through the opened nozzle hole.

[Embodiments of the invention]

Next, the present invention will be explained in detail based on embodiments shown in the drawings.

1 and 2, a heat insulating material 3 provided along the inside of an induction heating coil 2 formed by winding a hollow conductor;
A refractory material was stamped between the heating coil 2 and a frame (not shown) temporarily installed inside the heating coil 2 so that the central axes coincided with each other, and solidified by sintering and processing. Along the outer periphery of the heating coil 2 of the furnace body 1 consisting of the furnace wall 4a and the furnace bottom 4b, magnetic flux based on the magnetomotive force of the coil 2 leaks out of the furnace body and supports the frame and other parts of the furnace body l. A plurality of yokes 5 for magnetic flux convergence to prevent heating caused by passing through the structure are arranged and fixed symmetrically with their axes aligned with the direction of the axis of the furnace body 1. . At this time, cooling water flows through the hollow part inside the conductor of the heating coil 2, thereby cooling the coil itself.

As mentioned above, the furnace body 1 on which the yoke 5 is mounted has a gas inlet 8.
It consists of two parts: a lid 6a equipped with a pressure regulating valve 9 and a main body 6b equipped with a pressure relief valve 10 if necessary,
The seven flanges 17a and 17b are fastened together via a heat-resistant gasket 7 to keep the interior airtight from the outside world. The main body 6b of the closed container 6 includes a power supply means for the induction heating coil 2;
A water supply means for the hollow conductor of the coil 2 is attached by an appropriate method (not shown).

Furthermore, a nozzle support part 11 made of a material having rigidity and heat resistance, such as refractory brick, is provided to penetrate the furnace bottom 4b, and a through hole bored in the axial direction in the center of the nozzle 11 is provided. A cylindrical nozzle 13 made of graphite and having an appropriate outer diameter with a flexible heat insulating layer 12 formed by molding inorganic fibers such as ceramic fibers or glass wool with a heat-resistant binder on the inside. is fixed, and the bottom 6c of the airtight container 6 is fixed at the center of the nozzle 13.
A nozzle hole 13 having a predetermined inner diameter that communicates from the outside of the container 6 to the inside of the furnace body 1 through a hole 14 provided in the
a is formed.

On the other hand, a nozzle hole opening/closing rod passes through the lid 6a of the airtight container 6 and the refractory 15 provided with an internal number ζ, passes through the inside of the furnace body l, and reaches the inner opening of the furnace bottom 4b of the nozzle hole 13a. 16 is provided, and the nozzle hole opening/closing rod 1
By vertically moving the nozzle hole 1
The inner opening of 3a can be opened and closed. At that time, a shaft sealing device consisting of an appropriate heat-resistant gasket 18 is provided at the portion where the nozzle hole opening/closing rod 16 penetrates the lid 6a of the former sealed container 6, and the nozzle hole opening/closing rod is passed through the through portion of the lid 6a. Even though the container 16 moves up and down, the airtightness of the closed container 6 can be maintained.

In the crucible-shaped induction furnace of the present invention constructed as described above, the metal is heat-treated at a predetermined temperature in an atmosphere of air or a suitable inert gas with the closed container 6 closed, or the metal is heated in an open state. After heat-treating the metal in the same manner in the atmosphere, the hermetic container 6 is hermetically sealed, and then the air is heated to 1 to 1.8 kf/ through the gas inlet 8 provided in the lid 6a of the hermetic container 6 ad-at
Air or an appropriate inert gas having a pressure of about It becomes possible to freely pour or inject the heat-treated molten metal inside the nozzle 1 as a molten metal to the outside through the nozzle hole taa. At this time, the thermal insulation layer 12 interposed between the nozzle support part 11 and the nozzle 13 retains the temperature of the molten metal flowing out or injected from the nozzle hole 13a, and the molten metal is cooled and solidified in the middle of the nozzle hole 13a. This prevents inconveniences such as disconnection of 13a from occurring.

Therefore, in the crucible-shaped induction furnace of the present invention, by heat-treating the metal in an inert gas atmosphere in the sealed container 6, disadvantageous phenomena such as oxidation of the molten metal or contamination of impurities with the molten metal can be prevented. Therefore, by installing appropriate continuous casting equipment below the closed container 6 and pouring the inert gas under pressure through the gas inlet 8, high quality metal having a dense structure can be continuously produced. It has the advantage of being castable.

Further, in the case where the metal to be heat-treated in the closed container 6 in an inert gas in the crucible induction furnace of the present invention is aluminum, for example, the nozzle hole 1 is formed in the nozzle 13.
The molten metal is passed through the nozzle hole 13a into the powdered aluminum vote making device installed below the closed container 6 using an inert gas having a relatively small inner diameter and a pressure higher than atmospheric pressure. Another advantage is that powdered aluminum can be easily produced by injection.

Although the pressure of the gas introduced into the sealed container 6 can be freely adjusted by the pressure regulating valve 9 provided in the container body 6b, in any case the pressure of the gas does not exceed the specified safe pressure. If there is a possibility that the pressure exceeds the limit, protection can be provided by providing the pressure relief valve 10 in the closed container 6 as described above.

〔Effect of the invention〕

As explained above, the present invention provides a crucible-shaped induction furnace in which heat treatment such as melting of metal is carried out within the furnace body, which is equipped with an induction heating coil around the furnace wall in which refractories are stamped and sintered. , the furnace body is housed in the bottom of a closed container that is equipped with a means for introducing gas into the inside of the container wall and a means for adjusting the pressure of the gas inside, and a container is placed between the bottom of the container and the furnace main body. By providing a nozzle having a nozzle hole that penetrates the furnace bottom and opens into the inside of the furnace body, and by providing a means that can open and close the nozzle hole from above with the hermetic container sealed, the inside of the hermetic container is Since the atmosphere can be selected and its pressure adjusted, it is possible to prevent the oxidation of the molten metal heat-treated in the furnace body or the mixing of impurities, and also to prevent the nozzle hole from being oxidized by the pressurized gas introduced into the container. Since the molten metal can be poured or injected to the outside through the molten metal, it is extremely advantageous for continuous casting of high quality metals or production of powder metals.

[Brief explanation of the drawing]

Figures 1 and 2 show a longitudinal section and a schematic cross-sectional view of an embodiment of a crucible-shaped induction furnace according to the present invention, respectively, and Figure 3 shows a longitudinal section of a conventional general crucible-shaped induction furnace. Represents a schematic diagram. l...furnace body, 2...crocodile induction heating coil, 4a...
Furnace wall, 4b... Hearth bottom, 5... Yoke, 6... Sealed container, 6a... Lid of sealed container, 6b... Main body of sealed container, 6c... Main body of sealed container. Bottom, 8... Gas inlet, 9... Pressure control fi valve, 13... Nozzle, 13
a... Nozzle hole, 16... Nozzle hole opening/closing rod. 1st rM Figure 2

Claims (1)

[Claims] 1) In a pot-shaped induction furnace in which heat treatment such as melting of metal can be performed within the furnace body, which is equipped with an induction heating coil around the furnace wall where refractories have been stamped and sintered, the At the bottom of a closed container that houses a furnace body and is equipped with a means for introducing gas into the vessel wall and a means for adjusting the pressure of the internal gas, a hole is inserted through the bottom of the vessel and the bottom of the furnace body. A crucible-shaped induction furnace, characterized in that a nozzle having a nozzle hole opening into the inside of the furnace body is provided, and means for opening and closing the nozzle hole from above while the closed container is sealed is provided. .