JPS624870Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a crucible-type induction furnace, and particularly relates to an improvement in the structure to facilitate the removal of crucible material forming a melting chamber when the furnace is replaced.

Generally, if you continue to use an induction furnace for a long time,
The inner wall surface of the crucible is eroded by the molten metal, or cracks occur, resulting in a thinner wall thickness, which reduces the strength of the crucible, resulting in a very dangerous situation, and also has a negative effect on the melting effect. For this reason, it is necessary to periodically disassemble the refractory crucible that forms the melting chamber and replace it with a new one, which is called refurbishing.

Conventionally, when rebuilding a furnace, the crucible waste material that had been pulverized inside the furnace body was scraped out of the upper opening of the furnace body using a bucket, etc., or the furnace body was tilted and carried out through the upper opening. . When carrying out crucible waste in this way, dust from the crucible waste rises around the furnace body, which not only significantly deteriorates the working environment, but also has a negative impact on surrounding auxiliary equipment and other equipment, and furthermore, it is difficult to rebuild the furnace. The disadvantage was that it required a lot of effort and time.

For this reason, a crucible-type induction furnace has been developed in which a hole for carrying out the crucible waste material is formed in the refractory material of the hearth that supports the crucible from below, thereby making it easier to rebuild the furnace.

As shown in FIG. 1, this induction furnace includes an induction coil 1, a melting chamber 2 disposed within the induction coil 1,
a crucible 4 made of a refractory material 3 forming a crucible; a hearth refractory material 5 disposed below the crucible 4 and supporting the crucible 4; It consists of a hole 6 for carrying out the crucible waste material, which has an inner diameter smaller than the outer diameter of the crucible, and a furnace bottom cover 7, which is detachably attached to the hole 6 and is made of solid refractory material.

In the crucible-type induction furnace described above, when the furnace is rebuilt, the crucible 4 in the induction coil 1 is crushed, the hearth bottom cover 7 blocking the hole 6 opened in the hearth refractory material 5 is removed, and the hole 6 is removed. The crushed crucible waste material is carried out from the furnace and dropped into a pit 8 provided below the furnace body.

Therefore, since the crucible waste material is allowed to fall downward through the hole 6, the work is easy and the scattering of dust is relatively reduced.

However, since the furnace bottom cover 7 is made of solid refractory material such as cement and weighs more than 50 kg, when it is attached to and removed from the hole 6 for carrying out the crucible waste material lifted from the bottom of the furnace body, a machine such as a crane must be used. Since force cannot be used, three or more workers are usually required, and the positioning of bolt holes etc. is difficult and time consuming.

The object of the present invention is to eliminate the above-mentioned drawbacks, to provide a crucible-type induction furnace that can be easily rebuilt in a short time and has improved workability.

An embodiment of the present invention will be described in detail below with reference to the drawings.

2 to 4 show an embodiment of the present invention, 9 is a foundation, and a furnace frame 10 is placed on this foundation 9.
A furnace frame 10 composed of parts a and 10b is fixed. An induction coil 1 is provided inside the furnace frame 10 to generate an eddy current in the metal to be melted by electromagnetic induction, and further inside this is a crucible 4 formed of a refractory material 3 that serves as a melting chamber 2. It is provided. The refractory material 3 is appropriately selected to be acidic, neutral, basic, etc. depending on the type of metal to be melted, and is constructed by a dry method, a wet method, or the like.

An upper lid 11 is attached to the upper end opening of the crucible 4 so that it can be opened and closed, and iron cores 12 are provided at predetermined intervals around the outer periphery of the induction coil 1 wound around the crucible 4. It serves as a return path for the magnetic flux generated from the induction coil 1.

FIG. 4 shows an enlarged view of the bottom of the crucible 4, and a hearth refractory material 5 is provided below the crucible 4 to support it. At approximately the center of the hearth refractory material 5, a hole 6 for carrying out crucible waste material is opened, which communicates the inside of the crucible 4 with the outside of the furnace body. This hole 6
The crucible 4 has an inner diameter smaller than its outer diameter, and a flange 13 having an L-shaped cross section is attached to the periphery of the opening at the lower end of the hole 6 so as to face downward.

In the hole 6 for carrying out the crucible waste material, a hearth bottom cover 7 made of solid refractory material such as concrete or brick is attached to and detached from the flange 13 by bolts or the like via a bottom cover flange 14 provided on the lower surface of the bottom cover 7. installed on.

The hearth bottom cover 7 is formed into a cylindrical shape with an insertion hole 16 opened in the center thereof, through which the hanging tool 15 is passed, and a small disc-shaped hole is formed at the lower end opening of the insertion hole 16 to close the hole. A lid 17 is detachably attached. A screw hole 18 is formed in the center of the small lid 17, and a hanging tool 1 connected to a wire rope 19 is inserted here.
The tips of 5 are screwed together to suspend the hearth bottom cover 7.

The insertion hole 16 is filled with a powdered refractory 20 with the hanger 15 removed, and a heat insulating material 21 is provided at the upper and lower portions of the insertion hole 16.

In the figure, 22 is an operating handle attached to the lower surface of the furnace bottom cover 7, and 23 is a water cooling cable that supplies current to the induction coil 1.

Therefore, the hearth refractory material 5 to which the hearth bottom cover 7 is attached, the crucible 4 supported above, the induction coil 1, the iron core 12, etc. are integrally installed in the furnace body frame 10, and the shaft 2
4 is rotatably fixed to a support base 25, and tilted about a shaft 24 by a hydraulic cylinder 6.

FIG. 3 shows a state in which the crucible 4 is being dismantled. A transport trolley 27 is provided below the crucible 4, and the upper part of the transport trolley 27 and the crucible waste material transport port opening in the hearth refractory material 5 are shown. A duct 28 communicating with the hole 6 is attached. This duct 28
An exhaust duct 30 is formed that branches off at the upper part of the exhaust fan 29 and communicates with the exhaust fan 29, and both the exhaust duct 30 and the duct 28 are made of a stretchable and flexible material.

According to the crucible-type induction furnace configured as described above, when the metal to be melted is put into the melting chamber 2 and the induction coil 1 is excited, an eddy current is generated in the metal to be melted, and the metal is heated by the generated Joule heat and melted.

If the insertion hole 16 opened in the center of the furnace bottom cover 7 is left hollow in this heated state, there is a risk that cracks will occur in the crucible 4 due to air expansion and uneven temperature distribution at the bottom of the crucible 4. However, in the present invention, since the insertion hole 16 is filled with the powdered refractory 20, it is possible to prevent the occurrence of cracks during operation. Furthermore, a heat insulating material 21 is provided above the insertion hole 16 filled with the powdery refractory 20 to block the transfer of heat from the metal to be melted, so that the powdery refractory 20
can prevent sintering.

When the induction furnace is used for a long period of time in this manner, the refractory material 3 on the inner wall surface of the crucible 4 is corroded by the molten metal and cracks occur, gradually decreasing the strength.

For this reason, it is necessary to periodically rebuild the furnace.
In this operation, first, the small lid 17 attached to the furnace bottom lid 7 is removed, and the powdered refractory 20 filled in the insertion hole 16 of the furnace bottom lid 7 is scraped out of the furnace body. In this case, the powdered refractories 20 are insulated by the heat insulating material 21, so they are not sintered and are held in powder form and can be easily discharged.

Next, as shown in FIG. 4, only the center portion of the refractory material 3 located at the bottom of the crucible 4 is crushed and removed to communicate the interior of the melting chamber 4 with the insertion hole 16. After this, the wire rope 19 connected to a crane or hoist is lowered from above the melting chamber 4, and the hanging tool 15 attached to the lower end is passed through the insertion hole 16.
The lower end of the small lid 17 is screwed into the screw hole 18 of the set small lid 17 again.

Next, the furnace bottom cover 7 is lightly lifted with a crane or hoist, and the bolts of the flanges 13 and 14 are removed, and then the furnace bottom cover 7 is suspended and the foundation 9
drop it off at

Next, as shown in FIG. 3, the carriage 27 is pulled under the furnace body, and the duct 28 is connected to the flange 13 provided in the hole 6 of the hearth refractory material 5 for carrying out the crucible waste material.

In this state, the refractory material 3 constituting the crucible 4 is crushed into pieces, and the crushed crucible waste material falls from the hole 6 opened in the hearth refractory material 5 through the duct 28 to the transport cart 27. will be loaded on. Dust is generated when the crucible 4 is crushed, but since the duct 28 is connected to an exhaust duct 30 that communicates with the exhaust fan 29, the dust is forcibly exhausted and can be prevented from scattering around the furnace body. can. The transport cart 27 loaded with crucible waste is moved to a predetermined location and disposed of there.

After the crucible 4 has been dismantled, the furnace bottom cover 7 is set in the hole 6 for carrying out the crucible waste material, which is lifted by the hoist 15 using a crane or hoist, and fixed with bolts, by reversing the procedure described above. Work can be done alone. After removing the hanger 15 from the small lid 17, the insertion hole 16 is filled with powdered refractory 20, and the upper part thereof is covered with a heat insulating material 21, and then the crucible 4 is constructed by a normal furnace construction method.

Therefore, according to the crucible-type induction furnace, by supporting the bottom cover 7 with the hanger 15 when rebuilding the furnace, the bottom cover 7 can be installed and removed by one worker. Moreover, since the crucible waste material is loaded onto the transport cart 27 through the duct 28 equipped with the exhaust fan 29, scattering of dust is prevented, a good working environment is maintained, and the influence on peripheral equipment is reduced. Can be done.

5 and 6 show other embodiments of the present invention. A notch groove 31 is formed radially on the outer periphery of the bottom cover flange 14 attached to the lower part of the furnace bottom cover 7, and a stopper 32 is provided protruding from the side thereof. Reference numeral 33 denotes an L-shaped support fitting, which supports the hearth bottom cover 7 by inserting the notch groove 31 into the support fitting 33 and rotating it.
Numeral 34 is a jack bolt which can be easily removed when the furnace bottom cover 7 comes into close contact with the hole 6 for carrying out the crucible waste material due to thermal expansion.

When installing the hearth bottom cover 7 with the above configuration, the hanging tool 15
With the furnace bottom lid 7 lifted up and fitted into the hole 6, insert the notch groove 31 of the bottom lid flange 15 into the support fitting 33, rotate it until it hits the stopper 32, and then fix it with bolts. Can be installed easily.

In addition, when removing, after removing the bolts, attach the furnace bottom cover 7 to the support fitting 33 using the jack bolts 34.
After lowering it to the position shown in FIG. 1 and separating it from the furnace body, it can be easily removed by rotating the notch groove 31 to the position of the support fitting 33.

In the above embodiment, the hanging tool 15 is screwed onto the small lid 17 to hang the hearth bottom cover 7, but the present invention is not limited to this, and the lower end of the hanging tool 15 or the hanging tool 15 can be used. Instead, the lower end of the wire rope 19 may be passed through the small lid 17, and a stopper may be connected to the penetrating tip to lift the hearth bottom lid 7.

As explained above, according to the present invention, an insertion hole is opened in the bottom cover of the hearth through which a hanging tool is passed, and work can be carried out by lifting it with a crane or hoist.
It is possible to obtain a crucible-type induction furnace that can be easily rebuilt in a short period of time and has improved workability.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional front view showing a conventional crucible-type induction furnace, FIGS. 2 and 3 are longitudinal sectional front views showing a crucible-type induction furnace according to an embodiment of the present invention, and FIG. 4 is a longitudinal sectional front view showing a conventional crucible-type induction furnace. FIG. 5 is a bottom view of a furnace bottom cover according to another embodiment of the present invention, and FIG. 6 is a cross-sectional view showing an enlarged bottom part, and FIG. 6 is a cross-sectional view taken along line A-A in FIG. FIG. 1... Induction coil, 2... Melting chamber, 3... Refractory material, 4... Crucible, 5... Hearth refractory material, 6...
Hole, 7... Furnace bottom cover, 13, 14... Flange, 1
5... Hanging tool, 16... Insertion hole, 17... Small lid, 1
9...Wire rope, 20...Powdered refractory, 2
1...Insulating material, 27...Transportation trolley, 28...Duct, 29...Exhaust fan, 31...Notch groove, 33...
...Supporting metal fittings.

Claims (1)

[Scope of utility model registration request] an induction coil, a refractory crucible arranged within the induction coil and forming a melting chamber, a hearth refractory material disposed below the crucible and supporting the crucible, and an opening in the hearth refractory material, In a crucible-type induction furnace consisting of a hole for carrying out crucible waste material having an inner diameter smaller than the crucible outer diameter, and a hearth bottom cover made of a solid refractory and detachably attached to this hole, the hearth bottom cover is It is characterized in that it is formed in a cylindrical shape with an insertion hole in the center for passing the hanger through, a small lid is detachably provided at the lower end opening of the insertion hole, and the insertion hole is filled with powdered refractory material. A crucible-type induction furnace.