JP2002179456A - Burning process of ferrite core and burning tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ferrite core burning process for sintering a J-shaped ferrite core with good dimensional accuracy and also to provide a burning tool used for the process. SOLUTION: This burning process involves using the burning tool in which a flat part and a curved part are continuously formed, and sintering a J-shaped ferrite core having a flat part and a curved part, wherein the burning of the J-shaped ferrite core is performed in such a way that the intersection line of the flat part and curved part of the burning tool and the intersection line of the flat part and curved part of the ferrite core completely overlap each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a firing method and a firing jig for a J-shaped ferrite core having a continuous flat portion and a curved portion.

[0002]

2. Description of the Related Art A J-shaped ferrite core having a continuous flat portion 4a and a curved portion 4b is mainly used for an IH rice cooker, and its appearance is shown in FIG. The J-shaped ferrite core is a plate having a width of about 10 mm and a thickness of about 5 mm, and has a flat part 4 a having a length of about 100 mm and a curved part 4 b having a radius of about 80 mm. When this J-shaped ferrite core is fired, a ferrite core molded body 5a (core before firing) is placed sideways on a plate-shaped firing jig 5b as shown in FIG. Has a flat surface 6c inclined at an angle of 10 ° to 30 °, and has a stopper portion 6d at a lower end of the flat surface 6c and a curved surface 6e at a higher end of the flat surface 6c. Jig 6 in which is formed continuously
b.

[0003]

Ferrite is a sintering material that has a thermal expansion of about 0% to 1% during a temperature rise process and a shrinkage of approximately 14% to 16% during a sintering process at a high temperature. It is the result of experiencing various shape changes. If it can be fired in a space that is completely unaffected by gravity or friction, the shape of the core will be mathematically similar before and after firing, but in reality it will be deformed by the influence of gravity and friction and will not be similar I will. For these reasons, various measures are required for firing ferrite in consideration of the finished size.

[0005] As shown in FIG. 5, in a method of baking a ferrite core molded body 5a on a plate-like baking jig 5b in a horizontal direction, the ferrite core 5a and the baking tool 5b are contracted during baking. The friction caused the angle between the flat portion 4a and the curved portion 4b to widen, resulting in a problem that a target dimension could not be obtained. In such a case, it is possible to prepare a molding die in consideration of the spread during firing, but the yield is poor and not practical.

Next, as shown in FIG. 6, a flat surface 6c inclined at an angle of 10 ° to 30 ° is provided, and a stopper portion 6d is provided at a lower end portion of the flat surface, and a higher end portion of the flat surface is provided. In the method of firing using a firing jig 6b in which a curved surface 6e is continuously formed, the angle between the flat portion 4a and the curved portion 4b is reduced by the weight of the ferrite core 6a itself during firing, or the flat portion is bent. The problem that 4a bends has arisen.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a method of firing a J-shaped ferrite core having a continuous flat portion and a curved portion, wherein the firing jig has a flat portion and a curved portion formed continuously. And firing the ferrite core so that the intersection of the flat portion and the curved portion of the firing jig overlaps the intersection of the flat portion and the curved portion of the ferrite core.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view of an embodiment of the present invention before firing, and shows a J-shaped ferrite core molded body 1.
It is sectional drawing which shows the positional relationship of the intersection line BB 'of a flat part and a curved part of (core before baking), and the intersection line AA' of a flat part and a curved part of the baking jig 2. The intersection lines AA ′ and BB ′ are arranged so as to overlap at the point P. FIG. 2 is a cross-sectional view after firing of the embodiment of the present invention, showing a positional relationship between the J-shaped ferrite core 3 and the firing jig 2 after firing. This indicates that the ferrite core 3 has contracted. FIG. 3 is a perspective view of a firing jig used in this embodiment. FIG. 3 is a perspective view of a firing jig according to the embodiment of the present invention.

The firing jig has a continuous flat surface 3a and a curved surface 3a.
b. Since it is designed in consideration of the contraction of about 15% during firing and the deformation and elongation in the vertical direction due to its own weight, there is a space between the curved portion of the molded body 1 and the curved portion of the firing jig 2. After firing, both the flat portion and the curved portion match, and the J-shaped ferrite core 3 is finished to the size of the firing jig 2.

When the compact 1 is actually loaded,
-Shaped ferrite core intersecting line BB 'is sintering jig intersection A-
Overlapping A 'is not an easy task. Therefore, the length L2 (FIG. 3) of the flat portion of the firing jig 2 is made to be the same length as the length L1 (FIG. 4) of the flat portion of the molded body 1, so that FIG.
As shown in the figure, the J-shaped ferrite core intersecting line B-
It is designed so that B 'and the firing jig intersection line AA' can be overlapped.

In FIG. 1, the intersection line BB 'of the J-shaped ferrite core 1 and the intersection line AA' of the firing jig 2 are matched (in practice, the deviation is kept within 3 mm). As a result, the J-shaped ferrite core 1 is bent at the point P and finished to the desired size. This is the same when the flat part of the firing jig is inclined, and the same failure occurs if the positional relationship between the ferrite core and the firing jig is poor.

[0011]

According to the present invention, a J-shaped ferrite core having a continuous flat portion and curved portion can be obtained without deformation.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment of the present invention before firing.

FIG. 2 is a cross-sectional view of an example of the present invention after firing.

FIG. 3 is a perspective view of a firing jig according to an embodiment of the present invention.

FIG. 4 is an external view of a J-shaped ferrite core.

FIG. 5 is a perspective view of a conventional firing example.

FIG. 6 is a sectional perspective view of a conventional firing example.

[Explanation of symbols]

 Reference Signs List 1 molded body 2 firing jig 3 ferrite core 3a flat surface 3b curved surface 4 core end surface 4a flat portion 4b curved portion 5 end surface 5a, 6a formed body 5b firing jig 6b firing jig 6c flat surface 6d stopper portion 6e curved surface

Claims (3)

[Claims] 1. A method of firing a J-shaped ferrite core having a continuous flat portion and a curved portion, wherein the firing portion has a flat portion and a curved portion formed continuously. A firing method for a ferrite core, wherein firing is performed such that an intersection line between a flat portion and a curved portion and an intersection line between the flat portion and the curved portion of the ferrite core overlap. 2. A firing jig having a jig intersection line between a flat portion and a curved portion, wherein the positioning mechanism is capable of positioning the intersection line between the flat portion and the curved portion of the ferrite core and the jig intersection line. A firing jig comprising: 3. The firing jig according to claim 2, wherein a corundum refractory obtained by sintering the raw material at a high temperature using fused alumina / sintered alumina having an alumina purity of 99.5% or more is used.