Heating – Work feeding – agitating – discharging or conveying... – Removable furnace bottom section or kiln cart
Reexamination Certificate
1998-04-30
2001-04-03
Lu, Jiping (Department: 3742)
Heating
Work feeding, agitating, discharging or conveying...
Removable furnace bottom section or kiln cart
C432S093000, C432S226000
Reexamination Certificate
active
06210158
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and apparatus for firing ceramic compacts used in electronic parts.
2. Description of the Related Art
In mass production of ceramic electronic parts and the like, green ceramic compacts are generally fired using a batch firing apparatus
1
a
such as set forth in FIG.
4
.
FIG. 4
is a cross-sectional view of the batch firing apparatus
1
a
, provided with a furnace
2
a
having a firing space
3
a
for green ceramic compacts therein. The furnace
2
a
comprises a furnace wall
4
a
including a ceiling and a side wall, a stage
10
a
as a hearth, a heater
5
a
provided along the furnace wall
4
a
in the furnace
2
a
, a gas inlet pipe
6
a
and a gas outlet pipe
7
a
provided in the ceiling of the furnace. Further, a lift
9
a
is provided under the stage
10
a
for raising and lowering the stage
10
a
. The furnace
2
a
is supported by legs
11
a.
In the firing process of green ceramic compacts using the firing apparatus
1
a
, a casing
8
a
including many green ceramic compacts is put on the stage
10
a
and placed in the firing space
3
a
in the furnace
2
a
. The firing space
3
a
is heated with the heater
5
a
to fire the green ceramic compacts while supplying a given gas through the gas inlet and outlet pipes
6
a
and
7
a
. After the furnace
2
a
is cooled to a predetermined temperature, the stage is
10
a
lowered with the lift
9
a
to remove the fired ceramic compacts.
Since cooling in the furnace
2
a
of the ceramic compacts, which is fired at a high temperature, to room temperature requires a long time period, it is proposed in order to achieve faster cooling that the stage
10
a
be lowered with the lift
9
a
while the fired ceramic compacts having a high temperature are cooled by direct exposure to the open air.
However, such rapid cooling of fired ceramic compacts results in deterioration and fluctuation of electric characteristics of electronic parts comprising ceramic compacts due to the unstable cooling atmosphere.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method and apparatus for firing ceramic compacts in which rapid cooling of fired ceramic compacts can be achieved in a stabilized cooling atmosphere.
In accordance with the present invention, a method for firing a green ceramic compact comprises the steps of: placing a casing containing a green ceramic compact into a firing tube made of a highly heat-conductive material so as to substantially close the casing; firing the green ceramic compact in a furnace; cooling the fired ceramic compact by directly exposing the outer surface of the firing tube to open air; and removing the casing from the firing tube.
In accordance with a second aspect of the present invention, a firing apparatus for a green ceramic compact comprises: a furnace which may be provided with a hearth comprising a first stage and a second stage, each being independently movable; and a firing tube in the furnace with a given space from the side wall of the furnace, the top of said firing tube perhaps being fixed to the ceiling of said furnace, the bottom end of the firing tube capable of being placed on the first stage loaded with a casing containing the green ceramic compact so as to substantially close the casing, the firing tube having a space for firing the green ceramic compact therein and being formed from a highly heat-conductive material.
In accordance with the method and apparatus for firing a ceramic compact of the present invention, cooling of the fired ceramic compact is performed by directly exposing the outer surface of the firing tube to open air after the casing containing the ceramic compact is loaded in the firing tube made of a highly heat-conductive material so as to substantially seal the casing away from open air. In such cooling of the fired ceramic compact, the firing space atmosphere in the firing tube is not disturbed by the open air but after the ceramic compact is fired, the firing tube is, and thus cooling can be stably achieved.
REFERENCES:
patent: 2948949 (1960-08-01), Schuffler et al.
patent: 3867093 (1975-02-01), Huttermann
patent: 4582681 (1986-04-01), Asari et al.
patent: 5221201 (1993-06-01), Yamaga et al.
patent: 5352395 (1994-10-01), Kallenbach et al.
patent: 5429497 (1995-07-01), Yamada et al.
patent: 5567152 (1996-10-01), Morimoto
Burns Doane , Swecker, Mathis LLP
Lu Jiping
Murata Manufacturing Co. Ltd.
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