JPS61206208A - Manufacture of ferrite core - Google Patents

Abstract

PURPOSE:To enable to split a core accurately and easily at the prescribed position, to enable to make the split surface very clear and to reduce the amount of polishing by a method wherein, when a core is going to be split, the core is split by making the best use of local deformation by heat by applying heat on a V-shape split groove, and a plane polishing work is performed on the split surface. CONSTITUTION:An E-type part 10, an I-type part 12, and the V-type split groove 14 located at the boundary part are formed in one body, and a non-split core is molded and sintered. At this point, said V-type split groove 14 is formed into a sharp tip angle as much as possible. When the split groove 14 is locally heated by contacting a finely pointed burner flame 16 to the groove 14 or by pressing a heat-ray heater 18 to the groove 14, thermal expansion is generated, a crack is generated at the sharp tip part of said split groove 14, and the split groove is accurately divided into an E-type core 20 and an I-type core 12. A split surface 24 only is plane-polished, the I-type core 22 is assembled with E-type core 20 without polishing the back side 28 of the split surface 26 of the I-type core 22.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for manufacturing an El type core or an Ul type core used as a magnetic core of a transformer, etc. In addition to dividing the I sub-core using physical expansion and contraction, the back surface of the split surface of the I sub-core can be used as a joint surface with another E-type or U sub-core when assembling the core, making manufacturing easier and reducing costs. The present invention relates to a method of manufacturing a ferrite core that can achieve the following.

[Prior Art] When constructing a magnetic core for a transformer or the like by combining an E-type or U-type core and an I sub-core, a method has conventionally been adopted in which the core is fired without division and then divided. In other words, a method in which the E-shaped or U-shaped part and the ■-shaped part have a V-shaped dividing groove at the boundary, but are molded into a continuous and integrated shape, fired, and then divided using the V-shaped dividing groove. It is.

This is because if an attempt is made to manufacture a core that is E-shaped or U-shaped from the beginning, it will often be bent or distorted during molding or firing, making it difficult to mass-produce cores with high dimensional accuracy.

In conventional technology, when dividing a core that has been fired without division,
For example, it was divided by applying an impact force using a pliers or the like. If the divided cores are combined as they are, the inductance will vary, so
After polishing the split surface of the empty core and the split surface of the empty core, they were assembled into a winding component as a magnetic core.

[Problems to be Solved by the Invention] As mentioned above, in the prior art, when splitting a core that has been fired without splitting, an impact force is applied using a chisel or the like. Since the location is not constant, the splitting misalignment of the retarder etc. tends to cause chipping (so-called chipping) on the surface directly exposed to light, and there are also disadvantages such as difficulty in mass production.

In particular, when chipping occurs, it causes variations in inductance, so polishing must be performed until chipping disappears, which poses a problem in that the amount of polishing becomes extremely large. Other polishing work on the split surface of ferrite is extremely troublesome and should be minimized, but in the conventional technology, polishing is performed on both the split surface of the E-type or U-shaped core and the split surface of the I-shaped core. The disadvantage was that it lacked mass production.

The purpose of the present invention is to eliminate the above-mentioned drawbacks of the prior art, to be able to accurately and easily divide at a predetermined position, and to make the dividing surface very clean, which requires less polishing. Another object of the present invention is to provide an improved method of manufacturing a ferrite core that can significantly reduce costs and facilitate manufacturing since only the splitting surfaces of the E-type or U-shaped core are polished.

[Means for Solving the Problems] The present invention, which can achieve the above-mentioned objects, is characterized in that, when dividing an undivided fired core, heat is applied to a V-shaped dividing groove formed in the core to locally divide the core. The splitting surface of the resulting E-shaped or U-shaped hollow core is divided from the acute angle part of the splitting groove by utilizing thermal deformation. This is a method of manufacturing a ferrite core configured to be assembled so as to be brought into contact with a divided surface of an empty core.

Therefore, the present invention focuses mainly on the fact that thermal expansion and contraction are used to divide the cores, and that firing can be performed with high accuracy through non-divided firing. A major feature is that the back surface is brought into contact with the dividing surface of the E-shaped or U-shaped core.

As a method of thermal division, a method of emitting a burner flame with a small nozzle or controlled flame to the V-shaped dividing groove, a method of applying a hot wire heater to the V-shaped dividing groove, etc. are adopted. They locally heat the part of the dividing groove and divide it by utilizing the difference in thermal expansion.

Of course, by heating the dividing grooves formed on one side of the non-divided fired core and cooling the dividing grooves formed on the other side, the core is divided by causing more thermal expansion and contraction. You can also do that.

[Production 1@] By heating the V-shaped dividing groove on one side of the core that has been fired without division, the core is locally heated, thermally deformed, and divided. This division occurs starting from the tip of the V-shaped dividing groove, which has a sharp acute angle, and therefore, unlike division using mechanical force such as a chisel, division begins at an extremely accurate position.

Cores subjected to non-divided firing do not bend or distort during molding or firing, making it possible to create extremely precise surfaces. Therefore, in the present invention, the contact surface of the I-shaped core with the E-shaped or U-shaped core is made using the back surface of the split surface as it is, without polishing. Therefore, since it is only necessary to flatten the split surface of the E-type or U-shaped core, the number of polishing steps can be reduced to half compared to the conventional process.In addition, chipping does not occur as in the conventional process, so the amount of polishing can be reduced. can be even less than that.

[Example] Hereinafter, the present invention will be explained in more detail based on the drawings. FIG. 1 is a perspective view showing an example of an undivided core;
Figures 3 and 3 are explanatory diagrams showing the dividing process according to the present invention.

First, as shown in FIG.
An undivided core, which has a V-made dividing groove 14 at the boundary with the mold part 12 but is continuous and integrated, is molded and fired. Here, the V-made dividing groove 14 is shaped to have a tip angle as sharp as possible. The method up to this point can be considered to be basically the same as that for manufacturing a conventional non-divided sintered body.

The first point in which the present invention is significantly different from the prior art is the method of dividing such an undivided core. That is, by applying heat to the V-shaped dividing groove 14 and utilizing local thermal expansion, the V-shaped dividing groove 14 is divided from the acute end portion thereof. Specifically, for example, as shown in Fig. 2, a narrow burner flame 1 is used.
6 to the V-made dividing groove 14, or as shown in FIG.
There is a method of pressing a hot wire heater 18 against the product dividing groove 14. In any case, by such a method, the vicinity of the V-made dividing groove 14 is locally heated and thermal expansion occurs, and a crack is generated from the sharp tip of the dividing groove 14, causing the parts to face each other as shown in FIG. It is precisely divided into the E-shaped core 20 and the ■-shaped core 12 at the dividing grooves formed on both sides.

In Figures 2 and 3, a method is adopted in which one of the dividing grooves is heated, but by heating one dividing groove and cooling the other dividing groove by applying a refrigerant or the like, the temperature can be increased even more sharply. It is also possible to divide by adding a gradient.

The end face of the core divided in this way has a V
Since the structure is such that division starts accurately from the acute-angled portion at the tip of the mold division groove, the positioning of the division plane is extremely accurate and no division deviation or chipping occurs. Therefore, the amount of polishing can be considerably reduced. In FIG. 4, the dividing surface is schematically drawn in a jagged manner to make the explanation easier to understand, but in reality, it is a clean cut-off surface and does not have as large an unevenness as shown.

The second point in which the present invention is significantly different from the prior art is that only the divided surfaces 24 of the divided E-shaped core 20 are polished. Furthermore, the ■-shaped core 22 is combined with the E-shaped core 20 as shown in FIG. 5 by using the rear surface 28 of the dividing surface 26 as it is without polishing it. In the case of an undivided sintered body, a major feature is that deformation can be suppressed to an extremely low level during shaping and firing, and the present invention utilizes this point even more effectively. (2) The back surface 28 of the divided surface of the mold core 22 is a surface formed facing the press mold, and together with the non-divided structure, extremely accurate surface precision is maintained even after firing. Therefore, even if the surface 28 is brought into direct contact with the divided polished surface of the E-empty core 20, almost no variation in inductance occurs.

Although one embodiment of the present invention has been described in detail above, the present invention is not limited to only this configuration. Needless to say, in the above embodiment, the same applies to the combination of the E empty core, the core, and the sub-core.

[Effects of the Invention] Since the present invention is configured to perform division using thermal deformation as described above, it is possible to perform division from the acute end portion of the V-shaped dividing surface with great accuracy, thereby reducing yield. In addition to significantly improving the polishing process, it also has the excellent effect of suppressing the amount of polishing to the necessary minimum.

Further, in the present invention, only the splitting surface of the E-type or U-shaped core is polished, and the I-shaped core is directly polished by using the back surface of the splitting surface.
Since it is configured to be assembled so as to come into contact with the split surface of a mold or U-shape, there is no need to polish the T-empty core C, which is an advantage in that it can significantly reduce the number of polishing steps and reduce costs. It has the following effects.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an example of an undivided sintered body, an explanatory diagram showing an example of a target dividing method, FIG. 4 is a side view of a divided core, and FIG. 5 is an example of a ferrite core according to the present invention. FIG. 10... E-shaped part, 12... Summer-shaped part, 14.
...V-shaped dividing groove, 16...burner flame, 18...hot wire heater, 2o...E9 core, 22...19 core, 24.26...dividing surface, 28...back.

Claims (1)

[Claims] 1. Obtain a sintered body in which an E-shaped or U-shaped part and an I-shaped part have a V-shaped dividing groove at the boundary, but are continuous and integrated, and heat is applied to the V-shaped dividing groove to create a localized The splitting groove is split from the acute end portion of the splitting groove using thermal deformation, and the splitting surface of the resulting E-shaped or U-shaped core is polished, and the back surface of the splitting surface of the I-shaped core is directly cut into the E-shaped or U-shaped core. A method for manufacturing a ferrite core, characterized by combining the cores so that they come into contact with a split surface of a mold core.