JPS6012751B2 - Groove induction furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention involves winding a primary induction coil around a closed iron core, and forming a secondary circuit by winding a molten coil in a groove for the secondary circuit formed of a refractory material so as to surround the open iron core. This invention relates to a groove-shaped induction furnace that heats molten metal by Joule heat generated by an induced current flowing in the groove of the refractory material. The object of the present invention is to provide a groove-shaped induction furnace that reduces eddy current loss in the induction furnace casing.

Normally, this type of groove induction furnace is similar in principle to a transformer,
It has a closed iron core in the center, and a primary induction coil is wound around its monopod.

This primary induction coil corresponds to the primary coil of a transformer, and the secondary coil is the molten metal filled in the groove formed by the refractory material as described above. It is connected to the bus section and is configured to form a one-turn secondary circuit surrounding the closed iron core. When a predetermined voltage is applied to the primary transfer coil, an induced secondary current flows in the groove, and the molten metal in this groove generates heat due to Joule heat. The magnetic field generated by this secondary current is extremely strong as it reaches tens of KA or more, and this magnetic field also leaks to the induction furnace casing as a leakage magnetic field, causing overcurrent loss as the overcurrent flows through the casing. This not only reduces the electrical efficiency of the induction furnace, but also causes the temperature of the induction furnace casing to rise significantly due to overcurrent. Conventionally, to deal with this, cooling water flows closely around the outer periphery of the induction furnace casing. Many have a tube wrapped around them to cool the casing. It is also possible to separate the induction furnace casing from the primary concession coil and the groove for the secondary circuit formed by the refractory material without providing this cooling pipe, but with this configuration, the groove type concession furnace It has the disadvantage that its weight and external dimensions are significantly large. The present invention has been made with this point in mind, and it is an object of the present invention to provide a groove-shaped induction furnace in which the leakage magnetic field reaching the induction furnace casing is minimized to reduce eddy current loss.

First of all, Figures 1 and 2 show this loose groove type induction furnace with a secondary structure, where 1 is molten metal, 2 is a refractory material for forming the molten metal into a groove type 2a for the secondary circuit, and 3 is a primary induction coil, 4 is a closed iron circuit forming a magnetic path for the magnetic field induced by this primary transfer coil 3, 5 is the refractory material 2,
and an induction furnace casing 6 made of a metal plate for holding the primary induction coil 3, closed loop iron core 4, etc. in a predetermined relationship (Fig. 7); is a cooling pipe through which cooling water flows. Now, in the relative arrangement shown in FIG. 7, when a current flows through the primary induction coil 3, a magnetic field 8 as shown by the arrow is generated.

Since a part of this magnetic field 8 enters the induction furnace casing, an eddy current flows through the induction furnace casing 5 and generates heat. In addition, in the part sandwiched between the primary induction coil 3 and the molten metal 1, the magnetic field due to the coil current and the magnetic field due to the current in the molten metal groove 2a overlap in the same direction, and the magnetic field is particularly strong in this part. As a result, the eddy current loss in the portion indicated by A in FIG. 7 becomes particularly large, and the electrical efficiency of the induction furnace is significantly reduced. This invention was made by paying attention to this point.
As shown in the embodiment shown in the figure, core pieces 7 made of a silicon steel plate divided into a plurality of pieces are arranged at predetermined intervals between the inner side of the induction furnace casing 5 and the refractory material 2 having a miso-shaped shape 2a. However, the magnetic field generated in the induction furnace casing 5 is actively dispersed to reduce the heat generation of the induction furnace casing.

As described above, according to the present invention, the iron D piece 7 made of a silicon steel plate divided into a plurality of pieces is provided inside the induction furnace casing 5 to actively disperse the magnetic field generated in the casing.
are arranged at predetermined intervals, the eddy current loss in the induction furnace casing 5 is significantly reduced throughout the induction furnace casing 5, and the electrical efficiency of the groove-shaped induction furnace can be significantly improved.

Therefore, not only is it not necessary to increase the size of the induction furnace casing as one of the means to reduce the generation of eddy currents, but also the pump and cleaning tower, as well as the long piping Since there is no need to dispose an expensive cooling pipe 6 that requires the like, it is possible to provide a groove-shaped induction furnace that is small and can reduce costs. Note that FIGS. 5 and 6 show another embodiment of the present invention, in which an iron core piece 7 made of a silicon steel plate or the like is arranged particularly in a portion of the induction furnace casing 5 close to the primary induction coil 3. This arrangement was made because the magnetic field is particularly strong in the area close to the primary transfer coil 3.

Therefore, there is an effect that the eddy current loss in the part of the induction furnace casing 5, particularly in the vicinity of the primary induction coil 3 where the magnetic field is strong, is significantly reduced.

[Brief explanation of the drawing]

1 and 2 show a conventional groove-type induction furnace, with FIG. 1 being a longitudinal cross-sectional view, and FIG. 2 being a cross-sectional view along the row n line of FIG. 1. 3 and 4 each show an embodiment of the present invention, with FIG. 3 being a longitudinal sectional view and FIG. 4 being a sectional view taken along the line W--W in FIG. 3. 5 and 6 both show other embodiments of the present invention, and FIG. 5 is a longitudinal sectional view;
FIG. 6 is a sectional view taken along the line W--W in FIG. 5. 7th
The figure shows the relationship between the induction furnace casing, the primary transfer coil, and the closed iron core, and the distribution of the magnetic field. In the drawings, 1 is a molten metal, 2 is a refractory, 3 is a primary induction coil, 4 is a closed circuit core, 5 is an induction furnace casing, and 7 is a core piece. Note that the same reference numerals in the figures indicate the same or corresponding parts. i-th
Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7

Claims (1)

[Scope of Claims] 1. An induction casing made of a metal plate formed with a refractory material to form a groove for accommodating molten metal, and a primary induction coil wound around a closed iron core arranged so as to surround the groove. A groove-shaped induction furnace having a groove-shaped induction furnace, characterized in that core pieces of a silicon steel plate for dispersing the magnetic field generated in the induction furnace casing are divided into a plurality of pieces and arranged at predetermined intervals inside the induction furnace casing. shaped induction furnace. 2. The groove-type induction furnace according to claim 1, characterized in that a core piece is disposed inside the induction furnace casing adjacent to the primary induction coil through which the closed-circuit core passes.