JPS644074Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an induction melting furnace, and in particular improves the fastening structure of a return path core made of laminated silicon steel plates.

In general, an induction melting furnace has an induction coil 2 made of a water-cooled steel pipe wound around the outer circumference of a melting chamber 1 in the shape of a crucible made of a refractory material, as shown in Fig. 1, and an insulating plate 3 on the back side of the melting chamber 1. A plurality of return magnetic path cores 4 are arranged radially through the furnace frame 5, and each return magnetic path core 4 is supported by pressing bolts 6 attached to the furnace frame 5 toward the furnace center.

The return magnetic path core 4 prevents the magnetic flux generated from the induction coil 2 by electromagnetic induction from leaking to the outside to form an effective magnetic flux loop, and also supports the induction coil 2 from the outside to prevent the magnetic flux generated from the induction coil 2 from leaking to the outside. This serves to prevent deformation of the induction coil 2 due to thermal expansion.

As shown in FIGS. 2 and 3, the conventional return path core 4 is constructed by fitting a plurality of silicon steel plates 7 into a metal support frame 8 having a U-shape in plan view. . This support frame 8 includes two side plates 9, 9 arranged in parallel on both sides, and a plurality of presser plates 1 welded together at intervals along the longitudinal direction.
0, and the inner surface of the holding plate 10 is a concave curved surface, so by laminating and fitting the long silicon steel plates 7 therein, the front surface of the laminated core 11 (the back side of the induction coil) is , the curvature is the same as the curvature of the outer periphery of the induction coil 2.

However, such a conventional return path core 4
Since the structure is simply that the laminated silicon steel plates 7 are fitted into the support frame 8, the strength is not sufficient.
Thermal expansion of the melting chamber 1 due to molten metal is induced by the induction coil 2.
The return magnetic path iron core 4 gradually opened into a fan shape, and each silicon steel plate 7 was shifted and did not come into close contact with the back surface of the induction coil 2, making it impossible to prevent the induction coil 2 from deforming.

For this reason, as shown in FIG. 4, a structure can be considered in which bolt insertion holes 12 are drilled in a laminated core 11 made of laminated silicon steel plates 7, and stud bolts 13 are inserted into the bolt insertion holes and nuts 14 are used to connect each silicon steel plate 7 together to improve strength.

However, in this structure, it is necessary to form a concave curved surface on the front side of the laminated core 11 and to form a straight bolt insertion hole 12 inside. 15 must be opened at positions shifted one by one with respect to the width direction of the silicon steel plates 7. The holes 15 must be punched out one by one using a press, and the positions of the holes are shifted for each silicon steel plate 7 to form continuous straight bolt insertion holes 12 in a stacked state. It is actually difficult to do so from the viewpoint of processing and assembly.

Further, if the positions of the holes 15 of each silicon steel plate 7 are the same, processing becomes easier, but in a stacked state, each hole 15
The bolt insertion hole 12 formed by a series of
It has a curved shape as shown in the figure. in this case,
It is possible to insert the stud bolt 13 by bending it, but it is difficult to install the nut 14, and if the tightening strength is increased, the stud bolt 13 will deform into a straight shape, and the front surface of the laminated core 11 will become flat. Therefore, it will no longer come into close contact with the back surface of the induction coil 2.

Therefore, as shown in FIG. 6, it is considered that the inner diameter of the hole 15 formed in the silicon steel plate 7 is increased to form a curved bolt insertion hole 12 into which a straight stud bolt 13 can be fully inserted. It will be done. However, in this structure, the cross-sectional area of the bolt insertion hole 12 is large, and the effective cross-sectional area of the core is reduced, so the function as an iron core is deteriorated.

The purpose of the present invention is to eliminate the above-mentioned drawbacks, to obtain an induction melting furnace equipped with a return path core that is easy to process and assemble, minimizes the reduction in core cross-sectional area, and improves strength. It is something.

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

Hole 1 with an inner diameter slightly larger than the outer diameter of the insulating tube 16
5, two types of silicon steel plates 7a are prepared in advance: a silicon steel plate 7a that is punched and formed in accordance with the insertion position of the stud bolt 13, and a silicon steel plate 7b that is punched and formed with holes 15 shifted in position along the width direction. put.

A laminated core 11 is formed by laminating a plurality of silicon steel plates 7a.
A, laminated iron cores 11B, 11B with silicon steel plates 7b laminated on both sides thereof are arranged, and backing plates 17, 17 are provided on both sides, and a bolt insertion hole 12 is formed by continuation of the hole 15. Then, a stud bolt 13 whose surface is covered with an insulating tube 16 is inserted and lightly tightened with a nut 14. Next, the integrated laminated cores 11B, 11A, 1
1B, the front surface thereof is aligned with the same curvature as the back surface of the induction coil 2, and is firmly fastened with stud bolts 13 to assemble the return path iron core 4.

The return path iron core 4 has silicon steel plates 7a and 7b integrally fastened to the stud bolts 13, so its strength is improved and the induction coil 2 is reliably supported even by thermal expansion of the melting chamber 1. Deformation can be prevented.

In addition, since the laminated cores 11B, 11A, 11B can be formed by laminating two types of silicon steel plates 7a, 7b with different hole positions, punching of the holes 15,
Assembly work is easy. Moreover, the formed bolt insertion hole 12 has a small curvature at the center and a large discontinuous inner wall curvature on both sides, thereby forming a minimum curvature space into which a straight stud bolt 13 can be inserted, as shown in FIG. The reduction in the core cross-sectional area can be significantly suppressed compared to the conventional method.

In the above embodiment, a case was shown in which two types of silicon steel plates 7a and 7b were assembled with the opening positions of the holes 15 shifted, but a combination of three or more types may be used. However, from the viewpoint of workability and assembly, it is 2~
About three types are preferable. Also stud bolt 13
is not limited to the structure in which it is inserted into the insulating tube 16, but may be one in which the surface is coated with insulation.

As explained above, according to the present invention, processing and assembly are easy, the reduction in the core cross-sectional area is minimized, and
It is possible to obtain an induction melting furnace equipped with a return magnetic path core with improved strength.

[Brief explanation of the drawing]

Figure 1 is a longitudinal sectional front view of an induction melting furnace, Figure 2 is a cross-sectional plan view showing a conventional return path core, and Figure 3 is a
4 to 6 are cross-sectional plan views showing different conventional return path cores, and FIG. 7 is a cross-sectional plan view showing a return path core according to an embodiment of the present invention. 1... Melting chamber, 2... Induction coil, 4... Return magnetic path core, 6... Pressing bolt, 7, 7a, 7b...
Silicon steel plate, 8...Support frame, 11, 11A, 11B
...Laminated core, 12...Bolt insertion hole, 13...
Stud bolt, 15... hole, 16... insulating tube, 19... holding plate.

Claims (1)

[Scope of utility model registration request] In an induction melting furnace consisting of an induction coil wound around the outer periphery of a melting chamber and a plurality of return path cores arranged radially in close contact with the back surface of the induction coil, the return path cores are A laminated steel plate in which at least two or more types of silicon steel plates with holes drilled at different positions along a direction are laminated to form a continuous bolt insertion hole in which the curvature of the inner wall of the hole differs depending on the continuity of the holes; An induction melting furnace characterized in that it is formed from a stud bolt that is inserted into the bolt insertion hole and fastens the laminated steel plates together.