Press seal

An elastomeric seal suitable for use in sealing non-circular cylinders of hydraulic presses against loss of the working fluid. This seal is an elastomeric (e.g. rubber) seal having a generally L-shaped cross section. One portion of the seal functions as a support portion and includes longitudinally extending ribs along its inner face for engaging in a sealed relationship with a supporting structure. The other portion of the seal acts as a wiping portion in engagement with the moving cylinder. The wiping and support portions come together in a generally perpendicular relationship to form a rounded nose where their outer faces meet and a reinforcing fabric is formed into the seal along its outer surface and extending across the nose of the seal.

BACKGROUND OF THE INVENTION 
Hydraulic molding presses are well-known and have been used for a variety 
of purposes including the hot pressing of adhesive or resin coated fibers, 
chips or sheets of wood, paper and the like to form boards, panels, 
plywood and other products of a similar nature. 
The manufacture of wafer board panels from wood wafers and a heat curable 
resin is one such illustration. Numerous patents exist which refer to the 
manufacture of wafer board panels including patents to such inventors as 
James d'A. Clark and Robert Lambert. A useful description of the entire 
process is shown in U.S. Pat. No. 3,899,559. 
Although early efforts at making panels such as plywood and wafer board in 
hydraulic molding presses involve the use of relatively small presses of 
conventional design, economic realities have dictated the use of larger 
and larger presses. As the size of the presses has increased, concern has 
been generated over the ability of presses of conventional design using 
circular pistons to achieve uniform pressing and proper thickness control. 
In an effort to improve the operation of such processes, a hydraulic 
molding press was devised using an extremely large non-circular piston of 
approximately the same dimensions as the lower platen of the hydraulic 
press. This development is described in U.S. Pat. No. 2,875,797. 
The use of a hydraulic molding press having a non-circular piston of 
substantially the same size and substantially the same dimensions as the 
lower press platen offers certain advantages in quality control with 
regard to the product (e.g. wafer board) being produced. On the other 
hand, such presses must have an effective seal surrounding the 
non-circular piston for preventing loss of the working fluid (e.g. water). 
Conventional seals intended for circular pistons have not proven suitable 
and special seals have been developed, largely on a trial and error basis. 
Seal problems seem to have become more difficult as the size of the 
non-circular piston has been increased. For example, one single, 
non-circular piston press which is now in operation in the U.S.A. in the 
production of wafer board is approximately 8 feet wide by 28 feet long. 
Since changing a seal on a press of this size is a time consuming task and 
involves a complete shutdown of manufacturing operations, there has been 
substantial incentive to develop seals capable of operating for extended 
periods of time without replacement. 
SUMMARY OF THE INVENTION 
The present invention is an improved elastomeric seal. 
Briefly described, the improved seals of this invention are elastomeric 
(e.g. tire rubber or the equivalent) seals having a generally L-shaped 
cross section. One arm or leg of the L-shaped cross section functions as a 
support portion of the seal and the other leg functions as a wiping 
portion. The support portion is provided with a series of longitudinally 
spaced perforations for receiving means such as bolts for clamping the 
seal in an operating position. The inner face of the support portion of 
the seal is further provided with longitudinally extending ribs which 
embrace the perforations to thereby engage in a sealed relationship with a 
supporting structure when the seal is clamped in place. The wiping portion 
of the seal is intended to come into sliding contact with the moving press 
piston. The wiping portion and the support portion of the seal are joined 
together in a generally perpendicular relationship to thereby form a 
rounded nose where the outer faces of these two portions meet. A 
reinforcing fabric is formed into the seal along its outer surface and 
extending across the nose of the seal.

DETAILED DESCRIPTION 
The installation and arrangement of press seals are shown in FIGS. 1 and 2 
in which a press seal generally designated by the numeral 1 is clamped to 
a supporting frame member 2 by bolts 3 which pass through a metal 
hold-down plate 4 through a perforation in seal 1 into threaded engagement 
with support member 2. The seal 1 thus surrounds piston 5 which is mounted 
for reciprocal movement in a vertical direction. The seals thus prevents 
the working fluid from escaping through the space between support member 2 
and piston 5. 
This arrangement is shown more fully in FIG. 2 in which the non-circular 
nature of hydraulic press piston 5 can be seen. 
The details of the present improved seal are more fully shown in FIG. 3. 
FIG. 3 is a cross section of the improved seal of this invention. 
According to FIG. 3, the present seal which is generally designated by the 
numeral 1 has a generally L-shaped cross section. 
For purposes of convenience, the seal 1 of FIG. 3 will be described as 
though the press piston 5 would always be mounted for movement in a 
vertical direction and powered from below. 
As shown in FIG. 3, the generally horizontal leg of seal 1 is the support 
portion of the seal. The support portion has an upper face 6 and a lower 
face 7. The support portion of seal 1 is provided with a series of 
longitudinally spaced perforations 8 for receiving means such as bolts 
(e.g. bolt 3 of FIG. 1) for clamping seal 1 into a sealed operating 
position against a support member (e.g. support member 2 of FIG. 1). Along 
the lower face 7 of the support portion of seal 1 are two longitudinally 
extending ribs (9 and 10) which embrace perforations 8 and which engage a 
support structure (e.g. support 2 of FIG. 1) when the seal 1 is clamped 
into operating position. 
As shown in FIGS. 2 and 3, the vertical leg of seal 1 forms a wiping 
portion of the seal and includes an outer face 11 and an inner face 12. 
The support portion of seal 1 and the wiping portion of seal 1 come 
together in a generally perpendicular relationship to form a rounded nose 
13 where their outer faces 11 and 12 meet. 
A reinforcing fabric generally designated by the numeral 14 is formed into 
the outer surface of seal 1 and extends across the nose 13 of seal 1. 
Reinforcing fabric 14 need not extend completely across the outer face of 
seal 1 as shown in FIG. 3, although such is preferred. In general, it is 
sufficient if the fabric extends across nose 13 and covers at least 50 
percent of surface 11 and at least a portion of surface 6. Desirably, the 
reinforcing fabric 14 will cover a sufficient portion of surface 6 to 
surround perforations 8, and may even extend down the rear face 5 of the 
support portion of seal 1. 
The seal 1 will be molded or otherwise formed from an elastomeric material. 
Automobile tire compositions and their equivalent (natural and synthetic 
rubbers) are particularly preferred. 
The reinforcing fabric 14 which is formed or embedded or bonded into or 
onto the surface of seal 1 and which forms an integral part thereof, can 
be any suitable reinforcing fabric. Fabrics of the type used to reinforce 
automotive tires are particularly well-suited for this purpose. In 
particular, woven fabrics made of synthetic polymeric materials (e.g. 
nylon) are particularly preferred because of their wear resistance and 
temperature stability, as well as their resistance to water and oils. 
It is especially desirable for nose 13 of seal 1 to be rounded rather than 
angular since the rounding seems to prevent galling of the seal during 
use. A suitable radius for nose 13 is one-eight inch or greater. 
In FIG. 4 is shown one of the earlier designs of a press seal for use with 
a hydraulic molding press having a large non-circular piston. As shown in 
FIG. 4, this seal included a reinforcing fabric which was embedded well 
within the body of the seal. The nose of the seal was angular rather than 
rounded to any significant degree and the lower face of the support 
portion was devoid of any sealing ribs of the type shown in FIG. 3. When a 
seal of this general construction was used on a large press (a heated 
press having a lower platen of approximately 8 feet by 28 feet), the 
useful life of the seal was on the order of several months of press 
operation as contrasted to the seal shown in FIGS. 3 which has 
successfully functioned for more than 8 months of press operation.