Presses – Reciprocating press construction – Plural movable platens on intersecting paths
Reexamination Certificate
1998-11-18
2001-12-04
Gerrity, Stephen F. (Department: 3721)
Presses
Reciprocating press construction
Plural movable platens on intersecting paths
C100S242000
Reexamination Certificate
active
06324970
ABSTRACT:
This application corresponds to Japanese Application No. 9-337742, filed on Nov. 20, 1997, which is hereby incorporated by reference in its entirety.
BACKGROUND
1. Field of the Invention
The present invention relates to a pressing device and a pressing method, and, more particularly, to a pressing device for pressing a ceramic stacked layer structure including ceramic green sheets placed upon each other, and to a method of pressing a ceramic stacked layer structure using the pressing device.
2. Description of the Related Art
A typical example of a laminated ceramic electronic part is a monolithic ceramic capacitor. In a typical structure of the monolithic ceramic capacitor, external electrodes are disposed on ceramic elements. The ceramic elements are made from ceramic dielectric material, and have internal electrodes formed thereon. These internal electrodes are electrically connected to the external electrodes.
Monolithic ceramic capacitors are ordinarily produced in the following way. Ceramic green sheets, with internal electrode patterns formed thereon, are placed in a stacked layer structure and pressed together. The resulting pressed structure is then cut at predetermined locations to form individual ceramic elements. Afterwards, external electrodes are disposed on each of the individual ceramic elements.
Ordinarily, the ceramic stacked layer structure consisting of ceramic green sheets placed upon each other is pressed in order to squeeze the ceramic green sheets together, as shown in FIG.
5
. The ceramic stacked layer structure
51
is set in a die body
52
and a top die
53
, and is then pressed or squeezed between the die body
52
and the top die
53
.
In order to press the stacked layer structure
51
and thereby squeeze the ceramic green sheets together, it is necessary to exert a high pressure on the stacked layer structure
51
. This means that the die body
52
must be able to withstand high pressures. Therefore, the die body
52
is ordinarily large and heavy. However, a large and heavy die body
52
cannot be easily handled in the pressing operation. As a result, the pressing operation cannot be easily performed.
Since the die body
52
is heavy, a light-weight container, or jig, must be separately provided for transporting the stacked layer structure
51
to a location where the pressing operation is performed. This means that an additional step must be performed to transfer the ceramic stacked layer structure from the separately provided container to the die body
52
of the pressing device. This transfer is troublesome to perform, and can also cause the ceramic green sheets of the ceramic structure to become misaligned, thereby degrading desirable properties of the monolithic ceramic capacitor.
SUMMARY
Accordingly, it is an object of the present invention to provide a pressing device for pressing a ceramic stacked layer structure, that is small and light and includes an easily handleable die body, and a corresponding method of efficiently pressing the ceramic stacked layer structure.
In accordance with an embodiment of the present invention, a pressing device for pressing a ceramic stacked layer structure includes a die body having a bottom portion or bottom plate and a side wall portion that form a recess. The recess can accommodate a ceramic stacked layer structure of ceramic green sheets placed upon each other. One or more mechanisms for holding and pushing or exerting force on the die are also provided, and each includes a contact member and a thrusting mechanism. The contact member contacts an outer peripheral surface of the side wall portion of the die body. The thrusting mechanism pushes the contact member against the side wall portion of the die body in a direction toward an inner peripheral surface side of the side wall portion, i.e., toward the recess, to thereby position and reinforce the die body. A top die is also provided for pressing the stacked layer structure against the bottom plate of the die body when the stacked layer structure is accommodated in the recess of the die body.
Since the contact members and the thrusting mechanisms support the side wall portions of the die body during the pressing operation and help the die body withstand the high pressures of the pressing operation, the required strength of the die body is less than that of a conventional die mold which must withstand the high pressures of the pressing operation alone without support. Therefore, the die body can be made small and light.
In an embodiment of the invention, the bottom portion and the side wall portion of the die body can be separated from each other. Consequently, the die body can be constructed with a greater degree of freedom, and handled more easily. Alternatively, the bottom portion and the side wall portion of the die body can be integral parts of the same component.
Since the die body can be made small and light, it can be conveniently used as a container for transferring a stacked layer structure. Therefore, it is no longer necessary to provide a separate container for transporting the stacked layer structure, and then transfer the stacked layer structure from the separately provided container to the die body. This simplifies the pressing operation and eliminates problems caused by misalignment of the ceramic green sheets that occurs when the stacked layer structure is transferred from the separately provided container. For instance, the above-described apparatus reduces damage caused to the stacked layer structure compared to the conventional die apparatus.
According to another aspect of the present invention, a method of pressing a stacked layer structure consisting of ceramic green sheets placed upon each other includes the steps of accommodating the stacked layer structure in the recess of the die body, and pressing the stacked layer structure in the recess of the die body between a bottom plate of the die body and the top die, while supporting the side wall portions of the die body and positioning the die body by pressing the side wall portions inward toward the stacked layer structure using the contact members and the thrust mechanisms.
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patent: 529254 (1894-11-01), Fink
patent: 2867002 (1959-01-01), Zalozecky
patent: 2880668 (1959-04-01), Cranke
patent: 3727545 (1973-04-01), Madsen et al.
patent: 4826419 (1989-05-01), Coste et al.
patent: 4990081 (1991-02-01), VanVoren et al.
patent: 5807455 (1998-09-01), Giordano et al.
patent: 2 227 713 (1990-08-01), None
patent: 6-091627 (1994-04-01), None
patent: 6-190815 (1994-07-01), None
patent: 6-297432 (1994-10-01), None
Burns Doane , Swecker, Mathis LLP
Gerrity Stephen F.
Murata Manufacturing Co. Ltd.
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