JPS5826988A - Detector for leakage of molten metal of 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] The present invention relates to a hot water leak detection device in an induction furnace.

In a crucible-type induction furnace, a leak detection device is installed on the inner peripheral surface of a coil provided on the peripheral side of the induction furnace.
If a leak occurs on the peripheral side of the pot, it is detected and appropriate measures are taken to prevent damage to the coil, loop, and yoke. This method of detecting a hot water leak includes a first antenna installed so as to be in contact with the hot water at the bottom of the crucible;
A voltage is applied between the second antenna formed of metal foil stretched around the outer circumferential surface of the lv crucible, and when a leak occurs in the refractory material forming the crucible, the first antenna and the second antenna are A hot water leak is detected by the current flowing between the two antennas.

However, in the past, no leak detection device was provided on the outer periphery of the bottom of the crucible in an induction furnace, and therefore, if a leak occurred at the bottom of the crucible, it could not be detected. There is a risk that the yoke may burn out and lead to a major accident. Conventional.

The reason why a leak detection device was not provided at the bottom of the crucible is that the second antenna of the leak detection device, which is installed on the outer circumferential surface of the crucible, is stretched in a mesh pattern over the entire length of the top and bottom of the coil and the entire inner circumference. For example, it is an aluminum or stainless steel foil with a thickness of 0.05 ff and a width of 50 m. The reason for using aluminum or stainless steel foil in a hot water leak detection device is the first (
a) As shown in detail in Fig. 1(b) in part A of the figure, the purpose is to remove the insulating material and a thin sandwich structure in the insulating part 102 and bring the coil and molten metal as close as possible to increase melting efficiency. . It was difficult to wrap the aluminum or stainless steel foil around the bottom of the crucible, for example, up to 50 ff from the bottom. That is, slack is likely to occur in this part when wrapping the foil, and if this slack becomes large, it will come into contact with the yoke, causing current to flow through the detection device and causing it to malfunction even if there is no leakage.

However, after a detailed investigation into the hot water leak accident, it was discovered that the bottom of the crucible was the area where hot water often leaked. As shown in FIG. 1(a), when molding the crucible 101, a refractory material such as 5i02 powder is spread on the bottom of the crucible and stamped, and then a mold corresponding to the first step is placed to form a cylinder. form a section. Therefore, the bottom part and the cylindrical part become a joint, and in order to maintain the uniformity and density of the refractory material, there are many leaks in this part. In other words, a foil-like material suitable as an antenna for detecting hot water leaks cannot be placed at the bottom of the coil.
Moreover, there are many leaks in this area.

The present invention has been made in view of the above-mentioned problems.In addition to the conventional second antenna on the circumferential side of the crucible, the purpose of the present invention is to provide a second antenna for detecting leakage over the entire circumference of the side of the bottom of the crucible. 8 antennas are provided, and a voltage is constantly applied between the hot water in the furnace and the third antenna, and when hot water leaks at the /L/pot section and the hot water comes into contact with the third antenna, a circuit is formed. It is an object of the present invention to provide a hot water leak detection device for an induction furnace that can eliminate the above-mentioned problems by detecting hot water leakage by detecting the flow of current.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

As shown in FIG. 2, in the induction furnace 1, a coil 4 is wound into a cylindrical shape in contact with the inner circumferential surface of a plurality of yokes 3 fixed to an outer frame 2, and the inner circumferential surface of the coil 4 is coated with mica. .

An insulating part 5 having a sandwich structure is wound around the second antenna, which is made of an insulating material such as a Teflon glass sheet and aluminum or stainless steel foil for detecting hot water leakage. The inner circumferential surface of this insulating portion 5 and the outer circumferential surface of the crucible 6 are in contact with each other.

The crucible 6 is constructed on a refractory material 7 that is a basic member of the induction furnace 1. A first antenna 8 penetrates the bottom 6a of the crucible 6 from below, and the upper end 8a of the first antenna 8 is connected to the surface of the bottom 6a to touch the hot water 9 stored in the crucible 6.
It is placed so that it is in contact with the A lead wire 10 is connected to the first antenna 8, and this lead MIO passes through the refractory material 7 and is connected to one terminal of a power source 11 provided outside the induction furnace 1. The other terminal of this power supply 11 is an ammeter 12
A lead wire 13 is connected to the other terminal of the ammeter 12 . This lead wire 18 passes through the refractory material 7 and is connected to the eighth antenna 14.

3(a) and 3(b) show in detail the B part shown in FIG. ) The eighth antenna 14 is embedded in the four parts 15b provided on the inner peripheral surface 15a of the coil insulating stand 15 that supports the lowest coil 1v4a of V4 from below. The recess 15b is located on the inner peripheral surface 1 of the coil insulating base 15.
Therefore, the antenna 14 is provided all around the inner peripheral surface 15H of the coil insulating base 15. The outer circumferential surface of the insulating material 5 is in contact with the inner circumferential surface 15a of the coil insulating stand 15 to prevent the antenna 14 from falling off. Third antenna 1 provided all around the inner peripheral surface 15a of the coil insulating stand 15
Both ends or one end of 4 are led out by a lead wire 13. Note that, for example, a Canthal wire is used for the third antenna 14.

The above explanation is based on the third case where the crucible 6 is molded through the insulating part 5 which has the second antenna inside the inner periphery of the carp/I/4.
Although the structure of the antenna 14 has been explained, in the case where the inner periphery of the insulating part 5 is reinforced with cement or the like over the entire upper and lower length of the coil/L/4 and the entire circumference, the third antenna 14 is reinforced with the coil insulating stand 15 as described above. However, as shown in FIG. 4, it can also be provided on the four parts 16b provided on the lower end inner peripheral surface 16a of the cylindrical cement reinforcing member 16. Note that in this case, the eighth antenna 14
In order to prevent the antenna from falling off, the third antenna 14 is held down with adhesive Teflon tape 17.

Now, if a hot water leak occurs at the bottom 6a of the crucible 6, when the hot water penetrates the refractory material forming the crucible 6 and comes into contact with the third antenna 14, the first antenna 8, the hot water 9, the third antenna 14. Lead wire 13, ammeter 12% power supply 11. ! j-
A circuit is formed by the lead wire 10 and current flows. As a result, the pointer of the ammeter 120 swings, and it is detected that a hot water leak has occurred.

As explained above, in the present invention, in addition to the conventional second antenna on the circumferential side of the crucible, an antenna that goes around the crucible once in an insulator provided along the circumferential side at the bottom of the crucible is provided. An eighth antenna is provided, a power source is connected between the third antenna and the first antenna provided on the crucible surface, and a voltage is applied between both antennas. When hot water comes into contact with
The system detects hot water leaks by detecting that a circuit is formed and current flows, so even though hot water often leaks, conventional foil antennas are difficult to install. Even at the bottom of the crucible, where the leak could not be detected, it is possible to detect the leakage, which makes it possible to prevent horizontal damage to the coil and yoke by taking appropriate measures.

[Brief explanation of the drawing]

FIG. 1(a) is a sectional view showing a conventional example, FIG. 1(b) is a partial sectional view of FIG. 1(a), FIG. 2 is a sectional view showing an embodiment of the present invention, and FIG. a) The figure is a partial sectional view of FIG. 2. FIG. 3(b) is a front view of FIG. 3(a), and FIG. 4 is a partial sectional view showing another embodiment of the present invention. 1... Induction furnace, 4... Coil, 6... Crucible, 8
...1st antenna, 9 Kawayu, 11... source, 14.
...Third antenna, 15...Coil insulation stand, 15b,
16b...Concavity-16...Reinforcing material patent applicant Fuji Electric Seizo Co., Ltd. Representative Patent Attorney Aoyama Fugai 2 Memachi (b) Figure $4 Figure

Claims (1)

[Scope of Claims] (1) A crucible-type induction furnace comprising a crucible made of a refractory material and a carp μ provided on the central side of the crucible. A first antenna is provided on the bottom surface of the crucible so that its upper end is in contact with the hot water in the crucible, and a first antenna is provided on the bottom circumferential side of the crucible between the outer circumferential surface of the crucible and the inner circumferential surface of the coil. a third antenna provided all around;
A power supply is connected between the first antenna and the third antenna, and if a leak occurs at the bottom of the crucible,
A hot water leak detection device for an induction furnace, characterized in that the occurrence of hot water leakage is detected by detecting the flow of current in a path of a first antenna, a third antenna, and a power source. (2. In the device set forth in claim 1. An induction furnace leak detection device in which the third antenna supports the coil from below in a recessed portion of the inner peripheral surface of the coil insulating stand. (3) Patent In the device according to claim 1, the third antenna is a coil μ provided between the crucible and the coil.
An induction furnace leak detection device installed in a recess in the inner peripheral surface of the lower part of the reinforcing material.