A platen for use in a clamping operation wherein a force is generated having a first direction includes a first wall having edges and a center area and at least first and second sides, wherein the first side is adapted to be positioned nearest the clamping operation. The platen further includes a second wall spaced from and substantially parallel to the first wall, wherein the first and second walls extend substantially transverse to the first direction of the force. An intermediate support structure is positioned between the walls and is used to direct the force from the edges of the first wall toward the center area of the first wall for substantially preventing non-uniform deflection of the first wall along the first side.

BACKGROUND OF THE INVENTION 
The present invention is directed to platens used with molding machines and 
presses, and more particular to a platen having a design which allows for 
minimum platen deflection at minimum platen weight. 
Injection molding platens are typically block shaped as shown in U.S. Pat. 
No. 5,188,850 to Hirata et al.; U.S. Pat. No. 5,066,217 to Fukuzawa et 
al.; U.S. Pat. No. 5,110,283 to Bluml et al.; U.S. Pat. No. 5,162,782 to 
Yoshioka; and U.S. Pat. No. 5,192,557 to Hirata et al. In each of these 
patents, the mold platen is substantially block shaped having a 
substantially rectangular side which supports a mold half. During clamp-up 
of mold halves, a force is generated against the mold mounting face of the 
platen. As is typical with such block shaped platens, the mold mounting 
face is caused to concavely deform, forcing the top and bottom edges of 
the side towards the oncoming force and causing the platen to bend and 
provide tension across the backside of the mold platen. As a result, under 
the clamp-up force the center of the platens separate causing a gap 
between the mold halves, and in some cases, the formation of flash is a 
by-product. 
U.S. Pat. No. 4,615,857 to Baird discloses an encapsulation means and 
method for reducing flash during mold operations. In accordance with this 
device, it is alleged that injection and transfer molding of plastic is 
performed in a manner that virtually eliminates flash. Deflection of the 
mold press therein is measured with the mold press in the clamping 
configuration. The support structure of the mold is arranged to apply an 
equal force to the mold face by configuring supporting pillars and bars 
such that they act as individual springs against the mold face and in 
response to the force generated while the mold is in the clamping 
configuration. The spring constants and the lengths of the supporting 
pillars and bars are calculated to account for the actual deflection found 
in the mold press and thereby producing a uniform pressure on the molds 
during clamping of the press. 
Accordingly, the flexure of the mold platens during mold sealing is 
measured and the compressibility of the mold mounting blocks of the device 
are adjusted as a function of lateral position on one or both platens in 
order to compensate for platen flexure, so that a constant force is 
applied to the parting surface of the mold, independent of lateral 
position on the parting surface. The stiffness and length of the mounting 
blocks define the force provided by the mounting blocks and are determined 
in accordance with predetermined formulas depending upon the position of 
the block on the platen and the predetermined platen deflection. While 
Baird compensates for deflection, the method and apparatus by which this 
is achieved is quite complex requiring individual designs for particular 
forces to be generated with particular molds. Accordingly, a uniformly 
applicable design is not achieved. 
FIGS. 1a and 1b disclose a prior art molding platen having a shape slightly 
different than the block shape platens discussed above in the cited 
patents. As shown in FIG. 1a, the mold platen has a profile including 
several openings therethrough, a front wall and a back wall. As shown in 
FIG. 1b, a plurality of slots and ribs extend toward the back wall which 
can and has a smaller surface area than the front wall of the platen. The 
platen also includes bores at each corner thereof for receiving tension 
bars that resist the force F between the platens during mold clamp-up. 
Each tie bar carries a resistance force F.sub.R as shown. The plurality of 
ribs and slots are provided for decreasing the weight of the platen. That 
is, the front mold mounting face is under compression during mold clamp-up 
while the back wall is under tension as in a simple beam. The tie bars are 
drawn inwardly and deform to conform with platen face movement, as shown 
by the dotted line and arrows in FIG. 1a, thereby causing the mold face to 
bend and have a concave configuration during molding, similar to the 
platens of the aforementioned patents. Accordingly, despite the design of 
the mold platen of FIGS. 1a and 1b, mold face bending is not compensated 
for and the possibility of the creation of flash is still existent. Since 
both sides of the platen bend, the supports at the corners of the tie bars 
also bend resulting in uneven loading of the tie bar supports. This causes 
bending of the tie bars and high stress concentrations leading to 
premature fatigue failure. Arrows C show how the tie bars are bent during 
clamp-up. 
There exists, therefore, a need for a simply designed and lightweight 
platen which includes means for compensating for platen deflection during 
mold or press clamp-up and which substantially eliminates the creation of 
flash. 
SUMMARY OF THE INVENTION 
The primary object of this invention is to provide a mold platen for use 
with molding or clamping or pressing applications which results in 
substantially flat and parallel mold mounting faces during clamp-up. 
Another object of this invention is to provide a mold platen for use in 
injection molding applications as above which is lightweight. 
Still another object of this invention is to provide a mold platen designed 
to direct clamping force during clamp-up from the tie bars at the edges of 
the platen towards the center mold mounting area of the platen eliminating 
any curvature of the platen. 
Still another object of this invention is to provide a mold platen having a 
mold mounting face which stays almost completely flat during clamp-up and 
substantially prevents the formation of flash. 
And still a further object of this invention is to provide a mold platen 
having two walls and an intermediate support structure which prevents the 
mold platen from non-uniformly deflecting at the molding side during 
clamp-up. 
And yet another object of this invention is to provide a mold platen having 
two walls and a central arch-shaped intermediate support structure between 
the two walls which substantially prevents non-uniform platen deflection 
at the molding side. 
And yet another object of this invention is to provide a mold platen having 
two walls and an intermediate conically-shaped support structure for 
substantially preventing non-uniform platen deflection at the molding 
side. 
Another object of the present invention is to provide a mold platen for 
eliminating uneven loading of tie bars and nuts during clamp-up. 
The foregoing objects are achieved by the mold platen of the present 
invention for use in a clamping operation wherein a force is generated 
having a first direction. The platen includes a first wall having edges 
and a center area first and second sides, wherein the first side is 
adapted to be positioned nearest the clamping operation. The platen 
further includes a second wall spaced from and substantially parallel to 
the first wall, wherein the first and second walls extend substantially 
transverse to the first direction of the force. Means for directing the 
force from the edges of the first wall toward the center area of the first 
wall is provided for substantially preventing nonuniform deflection of the 
first wall along the first side. The purpose of the second wall is to 
resist the separation forces created by the intermediate structure. 
The details of the present invention are set out in the following 
description and drawings wherein like reference characters depict like 
elements.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawings in detail, there is shown in FIG. 2, an 
elevational and cross sectional view of a first embodiment of the platen 
of the present invention for use in a molding application, and in FIG. 3 a 
perspective view of the platen shown in FIG. 2, designated generally as 
10. Generally, platen 10 includes a mold mounting wall 12 adapted to hold 
a mold half 17, an end wall 14 and intermediate support structure 16 
positioned between molding wall 12 and end wall 14. 
FIGS. 4 and 5 represents additional embodiments of the platen of the 
present invention and from a general standpoint, the embodiments of FIGS. 
2, 4 and 5 are similar. FIG. 4 represents the particularly preferred 
embodiment, i.e. one with angled instead of arched walls or one having a 
conically shaped intermediate portion, as shown in FIG. 5. The foregoing 
and following description, unless otherwise indicated, applies equally to 
all embodiments and with regard to the figures, like numerals designate 
like elements. 
Mold mounting wall 12 is adapted to hold a mold half 17 for use in mating 
another mold half (not shown) for creating a mold and for sufficiently 
clamping the other mold half via clamping force F represented by the 
arrows. Reaction forces F.sub.R in tie bars 25 are further represented by 
the arrows. Mold mounting wall 12 is substantially rectangular in shape, 
although other shapes can be used, extends substantially transverse to 
force F, and preferably, on one of two platens on a machine, includes an 
aperture 18 through the center thereof for insertion of an injection unit 
20. As shown in the cross-sectional view of FIG. 2, the tip 22 of 
injection unit 20 preferably extends through aperture 18 to connect with 
mold half 17 thereby contributing to efficient space utilization. Mold 
mounting wall 12 also includes a bore 24 being substantially larger in 
diameter than tie bar 25 at each corner thereof for receiving tie bars 25. 
Mold mounting wall 12 is adapted to receive four tie bars 25 which extend 
therethrough and toward end wall 14. 
Intermediate support structure 16 provides a mechanism by which mold 
mounting wall 12 of platen 10 is prevented from non-uniformly bending 
during the application of clamping force F and as a result of such 
non-uniform bending, preventing the creation of flash and wear on the 
components of the molding machine. 
Intermediate support structure 16 includes one or more internal ribs 26 
and/or 28 extending from inner side 27 of mold mounting wall 12 to inner 
side 29 of end wall 14, causing the intermediate support structure to have 
a narrow end and a wide end. For the FIG. 5 embodiment, the intermediate 
support structure is preferably one continuous wall in a semi-spherical or 
conical shape which is attached to the end wall and mold mounting wall 
similar to as described below with respect to the upper and lower ribs. 
Ribs 26 and 28 are attached to and extend substantially outwardly from a 
central area 30 of inner side 27 of mold mounting wall 12, forming a 
narrow end, to the outer edges, 32 and 34, respectively, of the inner side 
29 of end wall 14, forming a wide end and cavity 31 between ribs 26 and 
28. Accordingly, central area 30 is located opposite the intended mold 
mounting area of mold mounting wall 12. Ribs 26 and 28 therefore support 
the platen face directly where the mold is located. Accordingly, in one 
embodiment, a singular upper rib 26 extends from central area 30 of mold 
mounting wall 12 to, and is attached with, an upper edge 32 of inner side 
29 of end wall 14. Preferably, upper rib 26 is attached to and extends 
across the entire width of inner side 27 of molding wall 12 as shown in 
the perspective view of FIG. 3, although this design may be deviated from 
as discussed below. Similarly, lower rib 28 is also attached to, and 
extends from central area 30, preferably along the entire width of inner 
side 27 of mold mounting wall 12 and is attached with the lower edge 34 of 
inner side 29 of wall 14. While ribs 26 and 28 have been described as 
substantially contiguous and extending across the entire width, the 
present invention also contemplates ribs 26 and 28 being comprised of a 
plurality of separate ribs having smaller widths and spaced from each 
other and not necessarily covering the entire width of the mold mounting 
and end walls. 
With particular reference to FIG. 2 and the embodiment shown therein, the 
resulting structure formed by upper rib 26 and lower rib 28 is 
substantially arch or C-shaped, wherein each rib is bowed outwardly 
relative cavity 31 of platen 10. 
Referring with particularity to FIG. 4 and the embodiment shown therein, 
upper rib 126 and lower rib 128 are substantially straight, extending from 
central area 130 to upper edge 132 and lower edge 134, respectively, of 
end wall 114. In this embodiment, the resulting shape is substantially 
V-shaped. The cross-section taken horizontally could be substantially the 
same to define another embodiment, i.e. such as the conical version shown 
in FIG. 5. As representative of the cross-section of the FIG. 5 
embodiment, FIG. 4 would not include holes 124 and the portion of tie bars 
125 seen in cavity 131 would not be seen since wall 226 would block the 
view. 
With particular reference to FIG. 5, and the embodiment shown therein, 
intermediate support structure 216 comprises a wall 226 which is conical 
or spherical in shape with the narrow portion of the conical or spherical 
shape attached to the inner surface 227 of mold mounting wall 212 and the 
wide portion of the conical or spherical shape attached to the inner 
surface 229 of end platen 214. The conical or spherical wall may be 
divided into sections for ease of manufacture, or may be a singular cast 
part. Due to the conical or spherical shape, the wall 226 of intermediate 
216 typically would not extend across the entire width of the end and mold 
mounting walls as described above for the FIGS. 2 and 4 embodiments. 
In the FIGS. 2, 4 and 5 embodiments, the upper and lower ribs of the 
intermediate support structure or wall of the conically or spherically 
shaped support structure are attached with molding wall 12, 112, or 212, 
respectively, at an acute angle .omega. thereto (not shown in FIG. 5, but 
similar to FIG. 4) and to end wall 14, 114, or 214, respectively, at an 
acute angle .alpha. thereto (not shown in FIG. 5, but similar to FIG. 4). 
End wall 14 is also preferably rectangular in shape, although other shapes 
may be used, and extends substantially parallel wall 12, transverse force 
F, and may include an aperture 36 therethrough in which injection unit 20 
can be adapted to extend for injecting melt into mold half 17. Similar to 
molding wall 12, end wall 14 includes bores 38 in alignment with bores 24, 
one at each corner thereof, in order to receive tie bars therethrough. 
Each of bores 38 may include, if necessary, a countersink 40 for receiving 
tie bar nuts 42. Upper rib 26 and lower rib 28 may also include openings 
48 and 50, respectively, therein and in alignment with bores 24 and 38 of 
walls 12 and 14 for receiving tie bars 25 as required. End wall 14 further 
can include purge openings 44 therein adjacent ribs 26 and 28, through 
which escaping melt, purgings and/or drool may exit from the platen by 
running down the inner surface 46 of lower rib 28 and through the purge 
opening 44. 
While the platens as shown are formed from a cast material, it is also 
feasible the elements thereof, i.e. the walls and intermediate support 
structure, may be formed separately and fastened together in any manner 
which will provide the necessary strength to withstand forces developed 
during clamp-up. 
In operation, platen 10 can be used, for example, with both movable and 
stationary platens used in molding machines and mechanical presses or 
other clamping mechanisms wherein deflection of a platen is possible due 
to clamp-up forces generated, and in both singular and tandem designs of 
these molding machines and presses and other clamping mechanisms. 
During clamp-up while using platen 10, intermediate support structure 16 
and the arrangement of mold mounting wall 12 relative intermediate support 
structure 16 is such that the clamping forces F at the edges of the 
platens are directed towards the center of the platen where the mold half 
is located, i.e functioning on a bridge principle to provide support 
directly under the mold. Accordingly, the mold mounting face of the platen 
deforms in a substantially parallel manner thereby substantially 
preventing bending and the creation of flash. 
The force F which develops on the mold mounting surface of platen 10 during 
clamp-up is indicated by the large arrow in FIG. 2. The force F acting on 
the platen during mold clamp-up is dissipated outwardly as forge F.sub.1, 
as indicated by the small arrows, along internal ribs 26 and 28 causing 
the intermediate support structure 16 to be in compression as indicated by 
the arrows C and causing the molding face of wall 12 to be in a neutral 
state in terms of bending forces acting unopposed thereon. In addition, 
end wall 14 is caused to be in tension as indicated by arrows T while the 
tie bars each with reaction force F.sub.R are pushed slightly outwardly 
due to stretching of end wall 14. As a result of this action of forces on 
and within the platen, the mold mounting face of molding wall 12 is not 
non-uniformly deflected. The force distribution described above is 
applicable equally to each of the embodiments enclosed herewith, i.e. the 
arch or C-shaped intermediate support structure and the V-shaped 
intermediate support structure shown in FIGS. 2 and 4, respectively and 
also the conically or spherically shaped intermediate support structure 
shown in FIG. 5. 
The primary advantage of this invention is that a platen is provided for 
use with molding or clamping or pressing applications which results in 
substantially flat and parallel mold mounting faces during clamp-up. 
Another object of this invention is that a platen is provided for use in 
injection molding applications which is lightweight. Still another object 
of this invention is that a platen is provided which is designed to direct 
clamping force during clamp-up from the tie bars at the edges of the 
platen towards the center mold mounting area of the platen, eliminating 
any curvature of the platen. Still another object of this invention is 
that a platen is provided having a mold mounting face which stays almost 
completely flat during clamp-up and substantially prevents the formation 
of flash. And still a further object of this invention is that a platen is 
provided having two walls and an intermediate support structure which 
prevents the mold mounting side of the platen from non-uniformly 
deflecting during clamp-up. And yet another object of this invention is 
that a platen is provided having two walls and a central arch-shaped 
intermediate support structure between the two walls which substantially 
prevents non-uniform platen deflection of the mold mounting side thereof. 
And yet another object of this invention is that a platen is provided 
having two walls and an intermediate conically or spherically shaped 
support structure therebetween for substantially preventing non-uniform 
platen deflection at the molding side. Another object of the present 
invention is to provide a mold platen for eliminating uneven loading of 
tie bars and nuts during clamp up. Since bending of the platen is 
minimized, the loading of the tie bars is substantially uniform and any 
resulting tie bar bending is substantially eliminated. 
It is to be understood that the invention is not limited to the 
illustrations described and shown herein, which are deemed to be merely 
illustrative of the best modes of carrying out the invention, and which 
are susceptible of modification of form, size, arrangement of parts and 
details of operation. The invention rather is intended to encompass all 
such modifications which are within its spirit and scope as defined by the 
claims.