Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
2000-03-10
2004-11-23
Vo, Peter (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S603200, C029S604000, C029S737000, C336S096000, C336S229000, C336S234000, C419S010000, C419S019000, C419S030000, C419S035000, C419S042000, C419S049000
Reexamination Certificate
active
06820323
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of firing magnetic cores, and more particularly, to a method of firing flattened-ring magnetic cores included in noise-suppressing components and other such apparatuses, as well as, a method of firing thin magnetic cores included in noise filters, inductors of transformers, and other such apparatuses.
2. Description of the Related Art
A flattened-ring magnetic core
21
shown in
FIG. 5
is known for use as a core in a noise-suppressing component. A signal line such as a flat cable is inserted into a flattened through-hole
22
of the magnetic core
21
, and high-frequency noise propagating through the signal line is eliminated. Typically, a cross section of the magnetic core
21
has a length L of a longer side of 10 mm to 100 mm and a length T of a shorter side of 1 to 10 mm, and the through-hole
22
has a length t of a short side of 0.3 mm to 8 mm. The magnetic core
21
is assembled and fired by providing a plurality of flattened-ring compact bodies, which are made of a ferrite material and are provided with the flattened through-holes
22
, at an opening surface thereof in a firing container (not shown in the drawing) so that the axes of the through-holes
22
are vertically oriented, and then firing the compact bodies
21
in this arrangement.
A thin magnetic core
210
shown in
FIG. 10
is known for use in a noise filter, an inductor of a transformer, and other such components. The core
210
is assembled and fired by arranging a plurality of thin compact bodies
210
made of a ferrite material vertically at one side thereof in a firing container (not shown in the drawing), and firing the compact bodies in this arrangement.
At this stage, each of the flattened-ring compact bodies
21
or the thin compact bodies
210
is spaced apart so that adjacent flattened-ring compact bodies
21
or adjacent thin compact bodies
210
do not stick together during firing. If the adjacent flattened-ring compact bodies
21
or the adjacent thin compact bodies
210
stick together, a chemical reaction may occur in the compact bodies when connected together or contacting each other, or breaks or cracks may occur when the connected compact bodies
21
or
210
are detached from each other by applying mechanical force.
With respect to the conventional method of firing magnetic cores, it is relatively easy to arrange the compact bodies
21
or
210
in a perpendicular orientation in a firing container in which they are placed with sufficient space when the compact bodies
21
or
210
are large, and in particular, when the compact bodies
210
are thick. In such a case, even if slight vibrations and shocks are applied, the flattened-ring compact bodies
21
or the thin compact bodies
210
are not inclined, and the adjacent flattened-ring compact bodies
21
or the adjacent thin compact bodies
210
do not easily stick together during firing.
However, recently, as magnetic cores become thinner and smaller, it is often necessary to fire small flattened-ring compact bodies
21
or small thin compact bodies
210
while they are vertically oriented and spaced apart from each other. In such a case, it is difficult to vertically position separately each of the small flattened-ring compact bodies
21
or the small thin compact bodies
210
. When the compact bodies
21
or
210
are small, slight vibrations easily cause the compact bodies
21
or
210
to be tilted, and the adjacent flattened-ring compact bodies
21
or thin compact bodies
210
are brought into contact with each other, and thus a chemical reaction may occur therebetween, or adherence, breaks, or cracks which are not visibly detectable may occur, resulting in an increase in the defect rate, or a decline in reliability of the product.
SUMMARY OF THE INVENTION
In order to overcome the problems described above, preferred embodiments of the present invention provide a method of firing magnetic cores in which firing is performed with a high degree of reliability and mass production is enabled.
According to one preferred embodiment of the present invention, a method of firing magnetic cores includes the steps of attaching a powder to the surface of a plurality of flattened-ring compact bodies made of a magnetic material and having flattened through holes, arranging the plurality of flattened-ring compact bodies adjacently so that the axes of the flattened through-holes of the flattened-ring compact bodies are vertically oriented, and firing the flattened-ring compact bodies while the powder is interposed between the adjacent flattened-ring compact bodies. The powder may preferably include an inorganic material or an organic material having particles with a particle size of about 1,000 &mgr;m or less.
In another preferred embodiment of the present invention, a method of firing magnetic cores includes the steps of attaching a powder to the surface of a plurality of thin compact bodies made of a magnetic material, vertically arranging the plurality of thin compact bodies adjacently, and firing the thin compact bodies while the powder is interposed between the adjacent thin compact bodies. The powder may preferably include an inorganic material or an organic material having particles with a particle size of about 1,000 &mgr;m or less.
The powder attached to the surface of the compact bodies functions as a spacer between the adjacent compact bodies. Therefore, the compact bodies can be arranged in the container by stacking them together, thus facilitating the setting operation. When the compact bodies are fired, the adjacent compact bodies are not brought into direct contact with each other, and thus inconveniences such as reactions in the contact surface therebetween, adherence, and breaks do not occur.
Other features, elements, advantages, steps and characteristics of the present invention will be described in more detail below with reference to the attached drawings.
REFERENCES:
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patent: 4876476 (1989-10-01), Kittaka et al.
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patent: 5935722 (1999-08-01), Moorhead
patent: 5977854 (1999-11-01), Mihara
patent: 6005468 (1999-12-01), Shirahata
patent: 6013318 (2000-01-01), Hunt et al.
patent: 6096966 (2000-08-01), Nishimoto
patent: 02239159 (1990-09-01), None
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Ito Nobuaki
Kino Hiroyuki
Nishinaga Yoshihiro
Keating & Bennett LLP
Kim Paul
Murata Manufacturing Co. Ltd.
Vo Peter
LandOfFree
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