JP3110281B2 - Holding container for molten metal induction heating device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a holding container suitable for promoting agitation and heating of a molten metal by induction electromagnetic force and induction heating in a process of refining and casting molten metal, for example, iron or aluminum.

[0002]

2. Description of the Related Art First, a conventional molten metal holding container using electromagnetic induction heating will be described. In the refining and casting processes of molten metals such as iron, copper or aluminum, electromagnetic induction heating has been applied to obtain defect-free and homogeneous products. For example, Japanese Utility Model Laid-Open No. 59-190455
In the gazette, in the casting process in the iron making process, an alternating current electromagnet is linked to a tundish, and induction heating is used.
An apparatus for maintaining a temperature suitable for a coagulation reaction in a mold and an example of means for controlling the voltage and current of an AC electromagnet are shown.

[0003] In the application example of the electromagnetic induction heating of the molten metal as described above, the heating mechanism is the same in any apparatus.
It utilizes Joule heat generated by inducing induced current in molten metal. Actually, the heating area and efficiency are adjusted by using multiple AC electromagnets, increasing the number of AC phases, and devising the spatial arrangement of them, taking into account the structure and shape of the refining equipment or casting equipment. I do.

[0004]

However, in the above-mentioned apparatus, it is necessary to improve the following points. The molten metal thermally expands due to heating by electromagnetic induction, and convection is generated. However, it takes a certain time to homogenize the temperature or the molten metal only by the convection. If the input power is increased to increase the convection in order to achieve the homogenization of the temperature and components in a short time, the power supply capacity of the power supply device increases, and the refining device and the casting device themselves increase in size. In addition, the increase in current also increases the temperature of the electromagnet coil, necessitating water cooling, and further increasing the size and complexity of the device. Further, since the electromagnetic force applied to the electromagnet increases, it is necessary to increase the structural strength of the AC electromagnet and the refining device. Increasing the power input increases the size and complexity of the power supply system equipment and increases the production cost in terms of energy consumption. Increasing the input power promotes electromagnetic interference to electromagnetic components of peripheral devices.

An object of the present invention is to solve the above-mentioned problems and to provide a holding container for an induction heating device which can efficiently stir while heating a molten metal and can finish a target operation in a short time. I do.

[0006]

In order to solve the above-mentioned problems, according to the present invention, there are provided two bathtubs provided in a refractory container main body for storing molten metal, and two planar bathtubs connecting the bathtubs. In a molten metal induction heating device having a parallel flow path and an alternating current electromagnet linked to one closed path formed by connecting the bathtub and the flow path, at least one horizontal surface of the flow path has a taper angle. A holding container for a molten metal induction heating device, characterized in that:

[0007]

The operation of the present invention will be described below with reference to the drawings.
FIG. 1 is a plan view of the holding container according to the first and second embodiments of the present invention, FIG. 2 is a side view of the first embodiment, and FIG. 3 is a side view of the second embodiment.

[0008] The usual holding container for induction heating of molten metal includes:
If there is one or more bathtubs, if there is one bathtub, a separate detour flow path of molten metal is provided in the bathtub, and if there is more than one bathtub, a flow path connecting the bathtubs is provided, A closed circuit including the flow path is formed. In order to efficiently heat the molten metal in the holding container, a closed circuit including a flow path 1 and a bathtub 2 is linked with an AC electromagnet composed of a coil and an iron core, as shown in FIG.

According to the present invention, not only convection but also stirring flow is added for the soaking and homogenization of the molten metal. For example, a taper angle is given to the flow path connecting the bathtubs to cut the flow path. Either the area is formed so as to change continuously from one bathtub to the other bathtub, or the taper angle and elevation angle of the flow path are set in the direction of travel arbitrarily set for the closed path composed of the bathtub and the flow path. In the same direction.

That is, as shown in FIGS. 1 and 2, a rectangular block-shaped container body 7 made of a refractory material whose outer surface is covered with an iron shell.
In the inside, two bathtubs 2 for storing the molten metal 3 are provided at intervals, and two flow paths 1 connecting the bathtubs 2 are formed on the bottom side of the container, and the bathtub 2 and the flow path 1 are connected. Coil 5 and iron core 4 linking to one closed circuit formed by
And an AC electromagnet composed of In this holding container, each of the two flow paths 1 is provided such that a taper angle is in a horizontal plane and both tapered portions are parallel to each other. The taper angle needs to be provided in at least one of the flow paths.

[0011] The taper angle of the flow path is approximately 15 ° to 45 °.
Range. When the taper angle is less than 15 °, it is difficult to give a flow to the molten metal, the amount of stirring is small, and when the angle exceeds 45 °, it does not contribute to the flow of the entire closed circuit. . This taper angle may be determined within the above range based on the geometric arrangement of the electromagnet, the flow path, and the bathtub.

In another example of the present invention, FIG.
As shown in FIGS. 3 and 4, an elevation angle is given to the flow path 1 having a taper in a horizontal plane. That is, each flow path 1
An elevation angle is provided from a small joining surface (inlet of molten metal) 10 to a large joining surface (outflow of molten metal) 11 of the two joining surfaces of the bath and the bathtub 2.

When a time-varying current 6 such as an alternating current or a pulse current is applied to the coil 5, a time-varying magnetic field 8 is generated in the iron core 4. Then, an induced current 9 is induced in the molten metal 3 so as to cancel the magnetic field 8. The induced current 9 turns clockwise or counterclockwise in FIG. 1 with the change in the magnetic field 8. Further, the induced current 9 flows through the molten metal 3 having resistance, so that Joule heat is generated, and the molten metal 3 is heated. Furthermore, the heated molten metal 3 thermally expands, and convection occurs due to the spatial distribution of heating.

On the other hand, during induction heating, since a magnetic field is also present in the molten metal 3, the Lorentz force 12
Occur perpendicularly to both. In FIG. 1, in the flow path 1,
Since the current tends to flow through the shortest path in a homogeneous material, the magnitude of the induced current 9 is large on the iron core side and small on the outer wall side, and most of the magnetic field generated by the electromagnet is concentrated in the iron core, In the flow path 1, the magnetic field generated by the induced current is stronger than the magnetic field generated by the electromagnet. As a result, the Lorentz force 12 in the flow path 1 becomes a pinch force whose core side is extremely strong toward the center of the cross section. Even if the direction of the current 6 changes, the Lorentz force 1
2 is always in the same direction, only the size changes. This Lorentz force 12 has a symmetrical distribution with respect to a horizontal plane because there is no taper angle in a normal holding vessel, and mixing of molten metal between bathtubs is hardly performed only by convection.

In the first embodiment of the present invention, a taper angle is provided in the flow path 1 symmetrically with respect to the center of the vessel, that is, the center axis of the coil 5 so that the direction of the strong Lorentz force 12 on the iron core side in the flow path is changed. The same point symmetry allows the molten metal in the flow channel to be extruded into the bathtub, that is, the molten metal flows toward the wide side of the cross-sectional area of the flow channel so that the molten metal can move between the bathtubs. Has become. The taper of the flow path is shown in FIG.
Also, it is desirable not to make it into a trumpet shape only in the horizontal plane as shown in FIG. Further, for the same reason, it is desirable to reduce the height and width of the flow path to such an extent that they do not greatly hinder inflow and outflow.

Further, in the second embodiment of the present invention, the taper angle is the same as that of the first embodiment, and the flow path 1 is formed as shown in FIG. An elevation angle is provided from the inlet 10 to the outlet 11. Therefore, when viewed from the side, the two flow paths intersect. The molten metal whose density has decreased due to thermal expansion flows in the elevation direction and easily moves to the other bath, and as a result, stirring is promoted. In order to perform such a function well, the elevation angle may be selected in the range of 0 to 20 ° in consideration of the coefficient of thermal expansion, density, electrical conductivity, viscosity, etc. of the molten metal, and the preferred range is It is around 18 °. If it exceeds 20 °, a static pressure is applied, which is not preferable.

It is desirable that the flow path 1 is provided at the bottom of the bathtub as much as possible so that convection of the molten metal thermally expanded by heating in the bathtub can be utilized.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings. The holding container of FIG. 1 has an outer dimension of 1200 mm (vertical) × 1200 mm excluding the AC electromagnet.
(W) x 700 mm (H). The channel has a taper angle of 18 ° in the horizontal direction, and no elevation angle is given. The container is made of refractory brick, and its outer wall and bottom are surrounded by a 5 mm thick steel shell. In the figure, the iron skin is omitted. Molten steel as molten metal 3 was poured into two bathtubs 2 until the liquid level reached 500 mm from the bottom of the bathtub. The coil 5 of the AC electromagnet was applied with an AC current having a turn number of 44, 680 A, and a frequency of 60 Hz. Current application start 1
For 10 seconds after 0 seconds, the time-average flow velocity in the direction perpendicular to the outlet surface at the point P on the boundary between the flow path 1 and the bathtub 2 linked to the electromagnet is determined by the heat resistance of the molybdenum cermet. When measured using a current meter, the average flow rate was 0.1.
It was 19 m / s. Thereafter, manganese powder was administered to one of the bathtubs, and a spectrum was observed at the liquid level of the molten metal in the other bathtub. The spectrum was detected after 41 seconds. Next, the induction heating was stopped, and immediately thereafter, while the heat convection was sufficiently large, the carbon powder was administered to one of the bathtubs and allowed to stand for 2 minutes. No carbon components could be detected from the bath.

Next, a second embodiment of the present invention will be described with reference to the drawings. The outer dimensions and material of the holding container are the same as in the first embodiment. The same is true for coating with iron skin. However, as shown in FIG. 3, the two flow paths are each provided with an elevation angle of 18 ° and cross each other. The charging height of the molten metal and the electrical conditions of the AC electromagnet are the same as in the first embodiment. For 10 seconds after the start of the current application, the time-averaged flow rate in a direction perpendicular to the outlet surface at a point P on the boundary line between the flow path 1 and the bathtub 2 linked to the electromagnet is measured with a heat-resistant current meter. As a result, the average flow velocity was 0.22 m / s. Thereafter, manganese powder was administered to one of the bathtubs, and the spectrum was observed at the liquid level of the molten metal in the other bathtub, and was detected after 35 seconds. The induction heating was stopped, and immediately thereafter, while the heat convection was sufficiently large, carbon powder was administered to one of the bathtubs and left for 2 minutes. No components could be detected.

As described above, according to the present invention, the stirring can be performed simultaneously with the induction heating of the molten metal without any additional equipment. In the present embodiment, molten steel is taken as an example of the molten metal, but the present invention is not limited to this example and can be applied to any molten metal such as aluminum, copper, and titanium. Further, even when the number of bathtubs and flow paths is further increased, the same effect can be obtained by applying the present invention to each closed circuit.

[0021]

According to the method of the present invention, not only heating by electromagnetic induction but also a stirring force is added, so that temperature or molten metal can be homogenized in a short time. In particular, since temperature equalization and homogenization can be performed without increasing input power, it is possible to avoid an increase in the power supply capacity of the power supply device, a rise in the temperature of the induction coil due to an increase in power, and an electromagnetic force applied to the induction coil. There is no need to increase the structural strength of the device. There is no increase in production costs because there is no change in energy consumption. Since it is not necessary to increase the input power, electromagnetic interference to electromagnetic components of peripheral devices is not promoted. The composition of the molten metal can be adjusted in a short time only by applying the alloy powder to one bathtub by the stirring force. Such effects can be expected, and efficient stirring can be performed while heating the molten metal.

[Brief description of the drawings]

FIG. 1 is a plan view of a holding container for molten metal showing a first and a second embodiment of the present invention.

FIG. 2 is a side view of a molten metal holding container according to the first embodiment of the present invention.

FIG. 3 is a side view of a molten metal holding container showing a second embodiment of the present invention.

FIG. 4 is a three-dimensional view of a molten metal holding container according to a second embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 flow path 2 bath tub 3 molten metal 4 iron core 5 coil 6 electric current 7 container body made of refractory material 8 magnetic field (inside iron core) 9 induced current 10 inflow 11 outflow 12 Lorentz force

Continuation of the front page (56) References JP-A-7-236952 (JP, A) JP-A-7-236951 (JP, A) JP-A-6-277811 (JP, A) JP-A-4-251636 (JP) JP-A-4-224060 (JP, A) JP-A-4-172155 (JP, A) JP-A-61-187557 (JP, A) JP-A-61-38755 (JP, A) 61-38752 (JP, A) Japanese Utility Model Hei 6-86849 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B22D 41/01 B22D 11/10 310 F27B 14/06 F27D 11 / 06 H05B 6/10 311

Claims (3)

(57) [Claims] 1. A bathtub provided in a refractory container body for storing molten metal, two planarly parallel flow paths connecting between the bathtubs, and the bathtub and the flow path formed in series. A holding container for a molten metal induction heating device, comprising: a molten metal induction heating device having an AC electromagnet linked to one closed circuit, wherein at least one horizontal surface of the flow path has a taper angle. 2. The holding container according to claim 1, wherein each of the two flow paths has a taper angle in a horizontal plane and both tapered portions are parallel to each other. 3. A taper angle is formed in each of two flow paths in a horizontal plane, and both taper portions are formed in parallel with each other. The holding container for a molten metal induction heating device according to claim 1 , wherein an elevation angle is provided toward the joining surface.