KR20080039500A - Electric conduction heating device - Google Patents

Abstract

An electric conduction heating device has an electrically conductive container (20), an upper electrode (16), and a lower electrode (12). The device heats a material received in the container (20) by supplying electricity to the container (20) with its the upper part and the bottom part held by the upper electrode (16) and the lower electrode (12). The container (20) has a lower barrel section (20a) and an upper barrel section (20b) that has a lower electric specific resistance value than the lower barrel section (20a). The electric conduction heating device can heat the received material efficiently.

Description

ELECTRIC CONDUCTION HEATING DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric conduction heating device, and more particularly, to an electric conduction heating device capable of dissolving and holding a metal such as aluminum or a material such as ceramic.

As a device for dissolving and holding a metal material to be cast, a combustion heater using a burner is known. However, such a combustion heating apparatus may cause deterioration of the working environment due to exhaust gas, noise, or the like, and when the molten metal is directly heated, metal materials may be contaminated by inflow or oxidation of gas. In addition, since local heating occurs easily, there is a problem that the uniformity of the material temperature is difficult. As the conventional heating method, indirect heating or induction heating using an electric heater other than the above-described combustion type is also known, but the former has a problem in thermal efficiency, and the latter has a problem of inflow of gas due to a stirring phenomenon.

For this reason, the electrically conductive heating apparatus which heats the material in a container by making an electric current pass through the container holding a metal material is known (for example, patent document 1). As shown in FIG. 3, the electrically conductive heating apparatus disclosed in Patent Document 1 has a structure in which a graphite crucible 53 is interposed and supported between an upper electrode 51 and a lower electrode 52. According to this electric conduction heating apparatus, since a current flows through the graphite crucible 53 by applying a voltage between the upper electrode 51 and the lower electrode 52, the entire graphite crucible 53 is heated, so that the received material is uniform. Can be heated.

Patent Document 1: Japanese Patent Application Laid-Open No. 7-167847

In the electrically conductive heating apparatus as described above, in order to maintain the molten state of the material, the graphite crucible has to be maintained at a high temperature for a long time, so there is a problem in that power saving becomes a problem.

The present invention has been made to solve such a problem, and an object of the present invention is to provide an electrically conductive heating device capable of efficiently heating a material.

The object of the present invention includes a conductive material, an upper electrode and a lower electrode, and a material contained in the container by causing a current to flow by the upper electrode and the lower electrode supporting the upper and lower portions of the container therebetween. An electroconductive heating device for heating a gas, wherein the container is achieved by an electroconductive heating device having a lower body portion and an upper body portion having a lower electrical resistivity value than the lower body portion.

Preferably, the electrical conductivity heating device has an electrical resistivity of 10 × 10 ^{−3 to} 500 × 10 ⁻³ Ω · cm of the lower body portion, and the electrical resistivity of the upper body portion relative to the electrical resistivity of the lower body portion. It is preferable that a ratio is 0.001-0.8.

In addition, the object of the present invention includes a conductive container, an upper electrode and a lower electrode, the current flows through the upper electrode and the lower electrode which is supported between the upper and the lower portion of the container to the current to the container An electrically conductive heating device for heating a contained material, wherein the container is achieved by an electrically conductive heating device having a lower body portion and an upper body portion thicker than the lower body portion.

In the conductive heating device, the thickness of the upper body portion is preferably 20% or more thicker than the thickness of the lower body portion.

In addition, it is preferable that the ratio of the height of the upper body portion to the height of the entire container of each of the electrically conductive heating devices is 0.05 to 0.3.

In addition, the conductive material is preferably interposed between the container and the upper electrode and between the container and the lower electrode.

In addition, it is preferable to further include a mounting table interposed between the container and the lower electrode to support the bottom of the container, wherein the mounting table preferably has a lower electrical resistivity value than the lower body portion.

1 is a plan view of an electrically conductive heating apparatus according to a first embodiment of the present invention.

2 is a cross-sectional view taken along the line A-A of FIG.

Figure 3 is a longitudinal sectional view of a conventional electrically conductive heating device.

* Brief description of drawing symbols *

1: electric conduction heater 2: casing

12: lower electrode 14: mounting table

16: upper electrode 20: container

20a: lower body portion 20b: upper body portion

22: conductive insulation

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. 1 is a plan view of an electrically conductive heating apparatus according to a first embodiment of the present invention, Figure 2 is a cross-sectional view taken along the line A-A of FIG. As shown in Figs. 1 and 2, the electric conductive heating device 1 is provided with a heat insulating material 4 such as a ceramic plate inside the casing 2 of a tubular shape, and a refractory brick or the like inside the heat insulating material 4. Fireproof material 6 is provided.

The lower electrode 12 in the form of a plate is horizontally disposed on the bottom surface of the casing 2 through the refractory material 6. The lower electrode 12 extends upward along the refractory material 6 and is connected to a conductive plate 12a protruding outward from the side surface of the casing 2. In addition, a mounting table 14 is installed on an upper surface of the lower electrode 12, and a container 20 is mounted on the mounting table 14.

The container 20 has a passage at the top, is formed of a conductive material, and is formed in the form of a crucible. The body portion of the container 20 is composed of a lower body portion 20a and an upper body portion 20b connected to an upper end of the lower body portion 20a, and the mounting table 14 and the upper body portion 20b. When compared with the electrical resistivity value of, the electrical resistivity value of the lower body portion 20a positioned between them is formed to be large. In the present embodiment, the electrical resistivity of the mounting table 14 and the upper body 20b is 5 × 10 ⁻³ Ω · cm, and the electrical resistivity of the lower body 20a is 100 × 10 ⁻³ Ω · cm. The thickness of the upper body portion 20b and the lower body portion 20a is about 24 to 30 mm. Table 1 below shows the chemical composition and physical properties of the mounting table 14, the lower body portion 20a and the upper body portion 20b in the present embodiment.

Table 1

characteristic Lower body part Upper Body Mount Conductive insulation Chemical Composition C SiC SiC ² Al ² O ³ [%] 30 33 22 10 [%] 35 41 9 8 [%] 73--18 Apparent porosity (%) bulk specific gravity 19.5 2.15 21.0 1.98 Unknown 0.9 Flexural strength (MPa) electrical resistivity (× 10 ^-3 Ωcm) 13.7 100 12.3 5.0 Unknown 2

The height of the upper body portion 20b is a height at which the material to be heated accommodated in the container 20 and the inner circumferential surface of the upper body portion 20b do not normally contact, that is, an appropriate amount of the material to be heated to the container 20. It is preferable that the liquid surface of the to-be-heated material melt | dissolved in the accommodated state is a height located below the connection part of the lower body part 20a and the upper body part 20b. More specifically, it is preferable that the ratio of the height of the said upper body part 20b with respect to the height of the said container 20 whole is 0.05-0.3, and it is more preferable that it is 0.1-0.2.

The container 20 can be manufactured, for example, as follows. First, the ratio of low electrical resistance materials such as graphite and high electrical resistance (insulation) materials such as alumina is adjusted to a predetermined electrical resistivity, and then mixed by liquid pitch tar or resin. Get clay. In this way, clays having different electrical resistivity are filled into the mold in a laminated form, press-molded, and then fired to give the required strength. And the container 20 can be obtained by processing into a shelf etc. as needed and making it into a predetermined shape.

In addition, an upper electrode 16 in the form of a ring is disposed above the container 20 in contact with the periphery of the opening of the container 20. The upper electrode 16 has a protrusion 16a protruding radially outward from the periphery, and a conductive plate 16b protruding outward from the side of the casing 2 is connected.

Clamps 18 are respectively provided at approximately the center of the upper edge at each side of the casing 2. The clamp 18 is provided with a lever 18a and a spring 18b, and is configured such that the tip of the spring 18b is in contact with the upper surface of the protruding portion 16a by the rotation operation of the lever 18a so as to be in a compressed state. do. In this case, the upper and lower portions of the container 20 may be interposed between the upper electrode 16 and the lower electrode 12 by the pressing force of the spring 18b. The upper part of the casing 2 is covered by a lid 19 with an opening formed at a position corresponding to the opening of the container 20, as indicated by broken lines in FIG. 2.

In addition, a conductive heat insulating material 22 is interposed between the lower electrode 12 and the mounting table 14, between the mounting table 14 and the container 20, and between the container 20 and the upper electrode 16, respectively. . As the conductive heat insulating material 22, one having excellent conductivity, heat insulating property, and adhesiveness is preferable. In this embodiment, a graphite gasket having a thickness of 3 mm is used (see Table 1 for chemical composition and physical properties). When using a graphite gasket, it is preferable that graphite carbon content is 50 to 100%. As said conductive heat insulating material 22, the woven sheet which used metals, such as aluminum, is mentioned elsewhere.

According to the electrically conductive heating device having the above configuration, the container 20 is accommodated with a material such as aluminum, and the conductive plates 12a and 16b are connected to a power source (not shown) such as a thyristor rectifier. do. In addition, a voltage is applied between the lower electrode 12 and the upper electrode 16 so that a current flows in the mounting table 14, the lower body portion 20a, and the upper body portion 20b. The material received is thus heated and melted to maintain this state.

In the present embodiment, the container 20 includes a lower body portion 20a and an upper body portion 20b, and the electrical resistivity of the upper body portion 20b is higher than the electrical resistivity value of the lower body portion 20a. Since the value is set low, when the current flows, the lower body portion 20a becomes a high temperature, and the temperature of the upper body portion 20b becomes lower than this. Therefore, the material can be sufficiently heated in the lower body portion 20a in which the material mainly contacts, and the heat generation can be suppressed in the upper body portion 20b having little contact with the material. Thereby, a material can be heated efficiently and power saving can be aimed at. In addition, the container 20 of the present embodiment is not only excellent in heatability, but also has an effect of obtaining good durability even without adjusting the atmosphere by an inert gas such as Ar or the like.

In addition, in the case where the container 20 is mounted on the mounting table 14 as in the present embodiment, the electrical mounting resistance 14 of the mounting table 14 is set lower than that of the lower body portion 20a. Can generate heat.

In the present embodiment, the upper body portion 20b and the mounting table 14 having lower electrical resistivity values are arranged above and below the lower body portion 20a, but the body portion of the container 20 Even when the upper and lower layers having lower electrical resistivity values are arranged above and below the intermediate layer as the layer structure, power can be saved as in the present embodiment.

In the container 20 of the present embodiment, when the electrical resistivity value of the lower body portion 20a is too small, a large current power supply is required, which makes it difficult to save power and at the same time in the junction between the current flow members. Inhibition of fever also becomes difficult. Moreover, when thickness is made too thin in order to increase electric conductivity, there exists a possibility that the function and durability as a container may fall. On the other hand, when the electrical resistivity of the lower body portion 20a is too large, a high voltage is required, so that discharge occurs easily. Therefore, the electrical resistivity of the lower body portion 20a is preferably 10 × 10 ^{−3 to} 500 × 10 ⁻³ Ω · cm, and preferably 50 × 0 ^{−3 to} 200 × 10 ⁻³ Ω · cm. More preferred.

In addition, the ratio of the electrical resistivity value of the upper body portion 20b or the mounting table 14 to the electrical resistivity value of the lower body portion 20a so as to obtain a good power saving effect is preferably 0.001 to 0.8, It is more preferable that it is 0.01-0.3. Preferred electrical resistivity values of the lower body portion 20a and the upper body portion 20b are, for example, in the manufacturing method of the container 20 described above, a mixing ratio of a low electrical resistance material and a high electrical resistance (insulation) material. It can set suitably by adjusting.

Further, in the present embodiment, between the container 20 and the upper electrode 16, between the container 20 and the mounting table 14, and between the mounting table 14 and the lower electrode 12, respectively, a conductive insulating material. Since 22 is interposed, the heat generated by the vessel 20 can be reduced by heat dissipation through the upper electrode 16 and the lower electrode 12. As a result, the material can be heated more efficiently.

In the present embodiment, by setting the electrical resistivity of the upper body portion 20b lower than the electrical resistivity of the lower body portion 20a, the lower body portion 20a is larger than the upper body portion 20b. Although the temperature is set to be high, the thickness of the upper body portion 20b is larger than that of the lower body portion 20a instead of varying the electrical resistivity values of the lower body portion 20a and the upper body portion 20b. By doing this, heat generation in the upper body portion 20b can be suppressed, and the same effects as in the present embodiment can be obtained.

The junction of the lower body portion 20a and the upper body portion 20b may be formed in a stepped shape, or may be formed in a shape in which thickness is continuously changed.

More specifically, the thickness of the upper body portion 20b is preferably 20% or more larger than the thickness of the lower body portion 20a. The thickness of the lower body part 20a in this case is 25-30 mm, for example. Although the upper limit of the thickness of the said upper body part 20b is not specifically limited, From a practical viewpoint, 60 mm or less is preferable.

According to the electrically conductive heating apparatus of the present invention, the contained material can be efficiently heated.

Claims (7)

An electrical conduction that includes a conductive container, an upper electrode and a lower electrode, and heats a material contained in the container by allowing current to flow by the upper electrode and the lower electrode which are supported between the upper and the lower parts of the container. As a heating device, The container includes a lower body and an upper body having a lower electrical resistivity value than the lower body. Electric conduction heater. The method of claim 1, The electrical resistivity of the lower body part is 10 × 10 ^{−3 to} 500 × 10 ⁻³ Ω · cm, The ratio of the electrical resistivity of the upper body to the electrical resistivity of the lower body is 0.001 to 0.8. Electric conduction heater. An electrical conductivity comprising a conductive container, an upper electrode, and a lower electrode, the current flowing by the upper electrode and the lower electrode supporting the upper and the lower parts of the container between the upper and lower electrodes, thereby heating the material contained in the container. As a heating device, The container includes an upper body portion thicker than the lower body portion and the lower body portion. Electric conduction heater. The method of claim 3, The thickness of the upper body portion is 20% thicker than the thickness of the lower body portion Electric conduction heater. The method according to any one of claims 1 to 4, The ratio of the height of the upper body portion to the height of the entire container is 0.05 to 0.3 Electric conduction heater. The method according to any one of claims 1 to 5, A conductive insulating material is interposed between the container and the upper electrode and between the container and the lower electrode. Electric conduction heater. The method according to any one of claims 1 to 6, Interposed between the container and the lower electrode, and further including a mounting table supporting the bottom of the container; The mounting table has a lower electrical resistivity value than the lower body part. Electric conduction heater.

Images