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Nov. 13, 1962
e. E. LAMB
‘ 3,063,363
Filed Jan. 18, 1960
Patented Nov. 13., 1962
outer edge surface of the bale and thus permits easier
George E. Lamb, Hoquiam, Wasl1., assignor to Lamb
Grays Harbor Co., lino, Hoquiam, Wash., a company
of Washington
Filed Jan. 18, 1960, Ser. No. 2,923
1 Claim. (Cl. 100-295)
This invention relates to presses as used in the paper
pulp manufacturing industry. More speci?cally stated,
the invention relates to improvements in presses that are
especially designed for the compressing of chemical cel
lulose pulp bales in order to increase the density of the
?ow of air within and its out?ow from the bale.
Yet another object of the invention resides in the pro
vision of an improved press platen, embodying the ob
jects and advantages above recited, whereby under con
trolled pressures a perfectly ?at top surface may be pro—
duced on the pressed and ?nished bale without lengthen
ing the retention period.
In accomplishing the above mentioned and other ob—
jects of the invention, I have provided the improved de
tails of construction, the preferred forms of which are
illustrated in the accompanying drawings, wherein:
FIG. 1 is an elevation of a typical pulp bale press
equipped, with a press platen embodying the improve
the bale; the latter being in order that a more favorable 15 ments of the present invention therein.
‘FIG. 2 is an enlarged sectional View of the platen,
ocean freight rate may be obtained where rates are based
taken on line 2—-2 in FIG. 1.
on the space occupied by the freight rather than on its
pulp and to decrease the thickness of space occupied by
‘Explanatory to the various objects and advantages
of this invention, it will here be pointed out that the
manner of pressing a paper grade pulp bale is quite
important for various reasons well known in the indus
try. A press, designed to properly press chemical cellu
lose bales, must be capable of applying a very light corn
pressing pressure, or a high pressure s-u?icient to “dead
press” the bale. In a modern, high ‘speed ?nishing room,
the press generally limits the production rate. The cycle
of the press and the “retention period” allowed for escape
of air from the pulp bale under compression will deter
mine the number of presses required to obtain a de
sired production. The retention period must be reduced
as much as possible in order to get the shortest pressing
FIG. 3 is an enlarged sectional detail taken on line
3-3 in FIG. 2 showing vacuum breaking air channels
and air escape ports.
FIG. 4 is a perspective view of the press platen ‘of
FIG. 1, removed from the machine and somewhat ex
aggerated in scale for better understanding.
FIGS. 5 and 6, respectively, are perspective views of
press platens of alternative forms.
The present invention anticipates that a platen, em
bodying the present improvements, is applicable, in its
use, to presses of various designs, makes and mecha
nisms and it is not the intent that it be restricted to the
30 type of press which has herein been shown as being
typical of pulp presses in general.
Before describing the present invention, attention will
be directed to the fact that, in the usual form of pulp
cycle. During the last twenty years the “retention period”
press, both the top and bottom platens have ?at and
has been reduced from approximately 60 to approxi
mately 15 seconds, by reason of utilizing increased press 35 parallel bale engaging surfaces. As a result, the cellu
pressures but the using of increased pressures has re
sulted in production of a greater percentage of “stickers”
and also has necessitated the installation of vacuum
breaker plates on the upper press platens in order to
prevent, in the opening of the press, the-lifting of the
bale from the lower platen and an incident dropping of
the lifted bale when the vacuum breaks.
lose ?bers in the bale are uniformly compacted since a
uniform compacting pressure is applied over the entire
top and bottom surface of the bale, and as a result, air
in the bale is trapped between the ?bers. Since the bale
is porous, the air will gradually escape and as it does,
the ?bers will bend to accommodate themselves to the
spaces originally occupied by the compressed air.
It has been observed that with higher pressures and
the increased speed of press closing, an increased length
in other pressing operations. For example, a pulp bale 45 of retention period has been required. Actually, a shorter
over-all press cycle was obtained by a slower applica
exerts a constantly increasing resistance to compression
tion of pressure that avoided air trapping.
as the pressing progresses and also, by reason of “spring
The basis of the present invention resides in so de
back” of the bale, exerts high but decreasing pressures
signing the contour of the platen that it ?rst comes in
on the press over a considerable distance as the press
contact with the center of the bale surface as the press
opens. The closing rate of a properly designed pulp
closes, subjecting the air contained therein at the center
press will decrease as the press pressure increases, so
to a greater pressure than at the edges, thereby bringing
as to utilize the full power of the pulp motor over the
about a faster out?ow of air from the bale, due to the
entire closing cycle and the press must have an adequate
delayed compression of the ?bers around the bale edges.
means of decompressing the bale.
‘It will also be called to attention that, in the normal
‘In view of the foregoing explanatory matter, it has 55
pressing by use of ?at surfaced platens, the center of
been the principal object of the present invention to pro
the bale is apt to be left slightly convex, unless an ex
vide an improved form of press platen for a pulp press,
cessive retention period is allowed; this by reason of
incorporating therein, certain novel vacuum breaking and
of ?bers about the bale edges while air
design features whereby the present “retention period”
for dissipation of air from the bale being pressed may 60 is still trapped or held in the bale center.
The designing of the present platen has been to re
be further reduced.
air trapping to a minimum and effect the progres
It is a further object of the present invention to pro
sive application of pressure to the bale from center to
vide a press platen with a bale engaging surface of novel
to the outer edges thereof to expedite the out?ow of
contour that, in use of the platen, in bale pressing, avoids
the trapping of air in the bale under compression and 65 air therefrom.
Referring more in detail to ‘the drawings.
expedites air exhaustion therefrom. Furthermore, it is
The press, herein shown in FIG. 1, is typical of
an object of this invention to so design the bale contact
presses to which the present platen may be applied. It
ing surface of the platen that the compression of the
comprises a base frame structure designated, generally
bale progresses from the inside areas to the outside areas
by reference numeral 10; an opposedly related upper
thereby bringing about a faster out?ow of air from the
structure 11 that is joined to and supported from the
bale and avoids compression of pulp ?bers about the
base frame structure by paired laterally spaced columns
The pressing of bales of dry pulp, especially at high
speeds, involves a number of factors not ordinarily found
surface contour and the vacuum breaking features are
quite desirable in order to obtain a shorter retention
period; a satisfactory flat surface on the bale, and a
12—12, disposed in parallel relationship. A cross-head
13 is slidably mounted on the columns 12—12 for move
ment toward and from the base frame. The base frame
structure 10 is horizontally disposed and mounts thereon
a bale supporting platform 10x upon which a pulp bale,
satisfactory release of the pressed bale in the opening
of the press.
What I claim as new is:
designated at 14, is here shown to be properly disposed
A pulp bale press of the character described compris
for pressing.
The means supplying power for opening and closing
ing a ?xed means for support of a stack of pulp sheets
or the like, a vertically movable means disposed for
the press is not herein shown in detail as it may be any
suitable source. It is herein represented as a hydraulic 10 movement toward and away from said ?xed means, and
a platen connected to the lower portion of said mov
cylinder 15.
able means, said platen comprising a unitary member
Fixed to the under surface of the cross~head 13 is a
having an upper surface and an opposed stack engaging
press platen 16 embodying the improvements of the
surface, said surfaces being connected by side surfaces,
present invention. This platen, as has been well shown
in FIGS. 2 and 4, is of rectangular form, and has hori
zontal dimensions that are preferably slightly greater than
the dimensions of the top surface of the bale 14 to be
pressed. The platen is ?xed to the underside of the
cross-head 13 in such position as to symetrically engage
the top surface of the bale incident to the closing of the 20
said upper surface being disposed adjacent the lower
portion of said movable means, said stack engaging sur
face being generally convex with the thickest portion
of the platen disposed at the central portion of the platen
and with the thinnest portion of the platen disposed
along peripheral portions of the platen so that the stack
engaging surface initially engages the top surface of a
press against the bale. The top surface of the platen
stack of pulp sheets at a medial point of the stack and
is ?at and is seated ?atly against and secured to the under
progressively engages such top surface toward the periph
surface of the cross-head 13 and it is formed from edge
eral edges of the top surface, said platen having a plu
to edge of this top surface with a plurality of air escape
channels 18 from each of which channels, air escape 25 rality of air ports formed therethrough, the lower ends
of each of said ports opening through said stack en
passages or holes 19 lead to the bale engaging surface
gaging surface, said upper surface having formed there
of the platen as best seen in FIG. 3; these holes being
in a plurality of spaced air channels extending substan
at relatively close intervals over the platen surface.
tially all the way across the upper surface of the platen,
An important feature of construction of this platen
resides in the contour of its bale engaging surface. It is 30 said air channels opening through at least one of said
side surfaces, the upper portions of each of said air
shown in FIGS. 2 and 4 that the bale engaging surface
ports opening into one of said channels with a plurality
is convex, both in its transverse and its longitudinal di
air ports opening into spaced portions of each of
rection. However, it might, in some instances be con
said channels thereby providing communication between
vex in one direction only, as has been shown in the
modi?ed or alternative form illustrated in FIG. 5. It is 35 the lower portion of said air ports at said stack engag
ing surface and atrnoshpere.
also proposed that such platens might also be made
with a ?attened pyramidal bale engaging surface such
as that of the platen of FIG. 6. In this latter device,
the pyramid has been merged into a spherically curved
tip, as designated by reference numeral 20.
In the pressing of a pulp bale, in a press using the
platen of FIGS. 2 and 4, the problem of exhausting air
long distances through the bale through highly compressed
?bers is accomplished. The same advantages reside in
use of the platens of FIGS. 5 and 6 by reason of the 45
progressive application of pressure from the bale center
The vacuum breaking details of the platens are not
necessary to the operation of exhausting air from the
bale, but are necessary to a satisfactory commercial op
eration of the press.
The combination of the platen
References Cited in the ?le of this patent
Antisell _____________ __ Nov. 12,
Noe __________________ __ Apr. 20,
Holthaus ___________ __ May 14,
Benedictus __________ __ Nov. 28,
Haefely ____________ .._ Nov. 13,
Ritchie _____________ __ May 21,
Smith ______________ __ Dec. 3,
Ireland et a1. ________ __ Feb. 2,
Loomis ______________ __ Oct. 5,
Johnson _____________ __ Aug. 22,
Harrison _____________ __ Dec. 9,
Robbins _____________ __ Oct. 12,
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