Presses – Plural presses – Stacked boxes or plates
Reexamination Certificate
2000-12-18
2003-04-22
Ostrager, Allen (Department: 3725)
Presses
Plural presses
Stacked boxes or plates
C100S092000, C100S199000, C156S583100
Reexamination Certificate
active
06550377
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a hot press apparatus and, more precisely, it relates to a hot press apparatus which can be advantageously used to form a laminate such as a printed circuit board which requires high precision.
2. Description of the Related Art
For instance, in a known multi-stage hot press apparatus which is used to obtain laminates (multi-layered products), such as printed circuit boards which are generally indicated at
80
in
FIG. 5
, a plurality of workpieces L, L, L to be multi-layered are placed between heating plates
85
,
85
,
85
in a chamber
82
on a machine bed
81
. A movable plate
86
is moved upward by a ram
88
to sequentially move the heating plates
85
upward in order to heat and press the workpieces L, L, L between the heating plate
85
on which the workpiece L is placed and the upper heating plate in each stage. Note that in the uppermost stage, the workpiece L placed on the uppermost movable heating plate
85
is heated and pressed between the heating plate
85
and the upper stationary heating plate
85
U to obtain the laminates (multi-layered products). In
FIG. 5
, numeral 83 designates the support posts,
84
the guide rails,
85
a
the stage,
87
the stationary plate, and
89
the thermally insulating plate.
In the apparatus as shown in
FIG. 5
in which the movable plate
86
is moved upward by the ram
88
, if the number of the heating plates
85
is large (e.g., not less than 15 stages), the height of the apparatus is in the order of several meters, and hence, it is necessary to emplace a cylinder apparatus
88
A for the ram
88
in a pit P formed in the floor surface F in order to adjust the height in connection with peripheral conveyor devices, etc., as can be seen in the drawings. However, the pit-type hot press is costly because many constructions or equipments are necessary. Moreover, it is difficult to modify the layout and to enlarge or relocate the apparatus.
To eliminate these drawbacks of the pit type hot press, in recent years, pit-less type hot press apparatuses in which no pit P is necessary have been proposed. As can be seen in
FIG. 6
in which a pit-less type hot press is generally indicated at
90
, the movable plate
96
is pulled up by the cylinder devices
100
toward the stationary plate
97
. In this structure, the height of the apparatus can be shortened by a height corresponding to the ram which is adapted to move the movable plate
96
upward, so that the pit P can be dispensed with. In
FIG. 6
, numeral 91 designates the machine bed, 92 the chamber, 93 the support posts, 94 the guide rails, 95 the heating plates, 95U the upper stationary heating plate,
95
a
the stage, 99 the thermally insulating plate, 109 the jack bolts for restricting the downward displacement, and L the workpieces (to be laminated), respectively.
However, the pit-less type hot press has the following drawbacks.
Namely, in order to pull the movable plate
96
up toward the stationary plate
97
by the cylinder devices
100
, it is necessary to connect pull shafts
101
of the cylinder devices
100
to the movable plate
96
at the outer peripheral edges
96
S thereof, in view of the presence of the heating plates
95
,
95
between the stationary plate
97
and the movable plate
96
. When the workpieces L are pressed by pulling the movable plate portions
96
S upward by the use of the pull shafts
101
, the movable plate
96
is deformed into a concave shape at the center portion thereof and the stationary plate
97
is also deformed into a concave shape at the center portion thereof on which the workpieces L are placed, as schematically shown in FIG.
7
. Consequently, the workpiece L tends to be deformed into a barrel shape in cross section in which the central portion is slightly bulged outward. This phenomenon is caused by a difference between the pressure applied to the central portion of the workpiece L and the pressure applied to the peripheral edge thereof. The non-uniform pressure leads to a non-uniform thickness of the workpiece L or the production of wrinkles or the presence of air between the layers of the laminate, etc., thus resulting in defective products. Note that, in
FIG. 7
, only one stage is schematically shown for clarity and the deformation is exaggerated and is actually on the order of a few tenths of a mm.
In particular, for a printed circuit board, through holes or a conductor pattern is formed in or on the hot-pressed laminate (substrate) L and the non-uniform thickness or the production of wrinkles or presence of air, etc., become more serious problems.
It is an object of the present invention to provide a hot press apparatus in which the advantages of the pit-less type hot press are preserved and the pressure can be uniformly applied to a workpiece to prevent the production of wrinkles or the presence of air in the laminate, whereby a high precision laminate product can be obtained.
SUMMARY OF THE INVENTION
To achieve the object mentioned above, according to an aspect of the present invention, there is provided a hot press apparatus in which workpieces are placed between heating plates in a chamber of a machine bed, so that the workpieces are heated and pressed by moving a movable plate toward a stationary plate to form a laminate, wherein the movable plate is held at its peripheral portions by shaft members and is moved toward the stationary plate by a drive means, and provision is made of a center portion pressing member at the center portion of the movable plate to press the substantially center portions of the heating plates.
Preferably, the center portion pressing member is provided with a pressing surface which covers the entirety or substantially entirety of the workpieces placed on the heating plates.
REFERENCES:
patent: 3241189 (1966-03-01), Siempelkamp
patent: 3826601 (1974-07-01), Hutter
patent: 4222724 (1980-09-01), van Hullen
patent: 4846925 (1989-07-01), Ishida et al.
patent: 4857135 (1989-08-01), Copp
patent: 4963221 (1990-10-01), Isobe et al.
patent: 0759345 (1997-02-01), None
patent: 09-057707 (1997-03-01), None
patent: 365572 (1999-08-01), None
Kabushiki Kaisha Meiki Seisakusho
Ostrager Allen
Self Shelley
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