U.S. patent number 3,850,213 [Application Number 05/400,754] was granted by the patent office on 1974-11-26 for continuous press.
Invention is credited to Clyde D. Keaton.
United States Patent |
3,850,213 |
Keaton |
November 26, 1974 |
CONTINUOUS PRESS
Abstract
A continuous press is disclosed for simultaneously pressing and
conveying a workpiece, such as the laminations for making plywood,
through the press is a continuous manner. The continuous press
comprises upper and lower platens upon which are mounted opposed
sets of presser-conveyor rails, which are spaced apart to receive a
workpiece therebetween. The presser-conveyor rails are mounted upon
the respective platens by means of plural cams (circular
eccentrics). Each set of rails drives a caterpillar belt and
preferably a sheet belt which encircles the platen supporting that
set of rails. The workpiece is interposed between the sheet belts.
The rails in each set are divided into plural groups and the
supporting eccentrics impart orbital motion to the rails in a
polyphase arrangement, i.e, the motion of each group of rails is
phase displaced from the motion of each group of rails. The two
opposed sets of rails are actuated synchronously with the
corresponding groups of rails and the two sets being 180.degree.
out of phase with each other.
Inventors: |
Keaton; Clyde D. (Woodstown,
NJ) |
Family
ID: |
23584869 |
Appl.
No.: |
05/400,754 |
Filed: |
September 26, 1973 |
Current U.S.
Class: |
100/154;
198/832.1; 100/311; 144/245.2; 156/583.5; 198/626.5; 198/832 |
Current CPC
Class: |
B30B
5/06 (20130101); B27D 3/04 (20130101); B30B
1/261 (20130101) |
Current International
Class: |
B30B
5/00 (20060101); B30B 5/06 (20060101); B27D
3/04 (20060101); B27D 3/00 (20060101); B27d
003/02 (); B27d 003/04 () |
Field of
Search: |
;156/583 ;100/151,154
;425/224,364,371,394,383,406
;144/281R,281A,281B,281C,281D,282,283,245A ;198/165,203 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Juhasz; Andrew R.
Assistant Examiner: Bray; W. D.
Attorney, Agent or Firm: Reising, Ethington and Perry
Claims
The embodiments of the present invention in which an exclusive
property or privilege is claimed are defined as follows:
1. Apparatus for simultaneously pressing and conveying a workpiece
comprising a first platen having plural cams rotatably mounted
thereon, a first set of rails disposed side-by-side with each rail
mounted upon a different one of the cams, a second platen having
plural cams rotatably mounted thereon, a second set of rails
disposed side-by-side with each rail of the second set mounted upon
a different one of the cams on the second platen, the first and
second set of rails facing in a direction toward each other and
spaced apart to accept a workpiece therebetween, means for rotating
the cams to impart orbital motion to the rails, said orbital motion
being in a plane parallel to said direction, the orbital motion of
the first set of rails being clockwise and the orbital motion of
the second set of rails being counterclockwise, said orbital motion
of a first rail in the first set of rails being of opposite phase
from the orbital motion of a first rail in the second set of rails,
said orbital motion of a second rail in the first set of rails
being phase displaced by a predetermined phase angle from the phase
of the orbital motion of said first rail in the first set of rails,
and said orbital motion of a second rail in the second set of rails
being phase displaced by said predetermined phase angle from the
phase of the orbital motion of said first rail in the second set of
rails.
2. The invention as defined in claim 1 wherein said predetermined
phase angle is equal to 360.degree. divided by the number of rails
in the first set of rails which are out of phase with each
other.
3. The invention as defined in claim 2 wherein the number of rails
in the first set of rails which are out of phase of each other is
equal to two.
4. The invention as defined in claim 2 wherein the number of rails
in the first set of rails which are out of phase of each other is
equal to three.
5. The invention as defined in claim 1 wherein at least one of said
platens is yieldably supported relative to the other whereby the
distance between the first rail in the first set of rails and the
first rail in the second set of rails remains substantially
constant throughout the orbital motion of the last mentioned rails
relative to said platens.
6. The invention as defined in claim 5 wherein said first platen is
supported in fixed position, hydraulic means supporting said second
platen, said hydraulic means including an hydraulic accumulator to
provide yieldable support for said second platen.
7. The invention as defined in claim 5 including first and second
rollers disposed at opposite ends respectively of said first set of
rails, a first endless link belt supported on said first and second
rollers and encircling said first platen and first set of rails and
in engagement with said first set of rails, third and fourth
rollers disposed at opposite ends respectively of said second set
of rails, a second endless link belt supported on said third and
fourth rollers and encircling said second set of rails and said
second platen and in engagement with said second set of rails, said
link belts each comprising multiple links in the form of rigid bars
spanning the respective sets of rails.
8. The invention as defined in claim 7 wherein each of said rigid
bars is disposed in edge-to-edge contact with the adjacent bars to
present a substantially continuous surface, said bars being of
tapered cross-section to provide clearance from the adjacent bars
when passing around said rollers.
9. The invention as defined in claim 7, including a first endless
sheet belt encircling said first endless link belt and movable
therewith and a second endless sheet belt encircling said second
endless link belt and movable therewith.
10. The invention as defined in claim 5, wherein each rail is
mounted upon multiple cams spaced longitudinally of each rail, all
cams supporting a given rail being connected with said means and
being rotated in phase with each other.
11. The invention as defined in claim 5 including a first cam shaft
mounted on said first platen and connected to the cams mounted
thereon, a second cam shaft mounted on said second platen and
connected to the cams mounted thereon, and separate bearing means
for each cam shaft adjacent each rail of the first set of
rails.
12. The invention as defined in claim 11, wherein each rail in said
first set of rails includes a web of narrower cross-section than
the head of said rail whereby the webs of the rails may be
separated by said bearing means and the heads of adjacent rails may
be more closely spaced than the webs.
13. The invention as defined in claim 5 wherein said cam is an
eccentric of circular curvature whereby said orbital motion of each
rail describes a circular orbit.
14. The invention as defined in claim 11, comprising a prime mover,
mechanical coupling means connected between the first cam shaft and
the prime mover and connected between the second cam shaft and the
prime mover, whereby said rails are moved in synchronism in their
respective orbital paths.
15. The invention as defined in claim 14, wherein said mechanical
coupling means comprises a first drive means connected between said
prime mover and said first cam shaft for driving the cam shaft in
one direction, and second drive means connected between said prime
mover and said second cam shaft for driving said cam shaft in the
opposite direction.
16. The invention as defined in claim 15, including plural
additional cam shafts rotatably mounted in said first platen, each
additional cam shaft including a separate cam coacting with each
rail in the first set of rails, said first cam shaft and each
additional cam shaft having a drive gear nonrotatably mounted
thereon and an idler gear rotatably mounted thereon, the drive
gears and idler gears all having the same number of teeth, said
first cam shaft and one of said plurality of additional cam shafts
being connected to said first drive means for rotation in opposite
directions, the drive gear on each cam shaft meshing with the idler
gear on each adjacent cam shaft, whereby all of the cam shafts
rotate in the same direction.
Description
FIELD OF THE INVENTION
This invention relates to apparatus for simultaneously pressing and
conveying a workpiece; more particularly the invention relates to
apparatus for continuous pressing of workpiece material while the
workpiece material is continuously conveyed through the
apparatus.
BACKGROUND OF THE INVENTION
The need for a continuous press capable of applying uniform and
high pressure continuously to a workpiece while the workpiece is
conveyed through the press has long been recognized. There are
numerous applications, such as the manufacture of laminated board
or composition particle board, which is performed by a
batch-process, even though a continuous process would be much more
efficient if equipment were available. The prior art reflects a
considerable effort to develop a continuous press capable of
applying high pressure uniformly over the surface of a workpiece;
however, it appears that heretofore the need for the continuous
press has not been met.
Among the major problems in devising a high pressure continuous
press is the problem of obtaining uniform pressure over the area of
the workpiece and the problem of producing continuous motion of the
workpiece through the press under high pressure without overloading
the bearings which support the moving press members. Where
anti-friction bearings of the rolling type have been used, the
small available bearing area results in high stresses and bearing
failure and if slide bearings are utilized to take advantage of
large bearing area, the sliding friction and resulting heat
generation are excessive and the device is impractical.
One type of prior art continuous press utilizes a pair of
oppositely rotating chains of platens which are spaced apart to
receive a workpiece therebetween. The platens are aligned in the
direction of movement and are driven continuously over guide
rollers or sprockets. Pressure is applied by hydraulic means to
compress the workpiece between the opposed chains of platens and an
anti-friction roller belt is provided on the backside of each of
the chain of platens to provide a roller type bearing for the
chains of platens. Such apparatus is disclosed in the Dyke Pat. No.
2,071,999 and also in the Lambert et al. Pat. No. 2,490,819. A
difficulty with this type of continuous press arises from the use
of roller belts disposed between plane surfaces as the bearing
members for supporting the continuously moving and heavily loaded
platens which engage the workpiece.
Another type of continuous press known in the prior art utilizes
two oppositely disposed sets of parallel bars with the bar of each
set extending in the direction of travel of the workpiece through
the press. The workpiece is compressed between a pair of bars, one
from each set, during a forward stroke of the pair of bars and then
is compressed between a second pair of bars, one from each set,
during a forward stroke of the second pair of bars. The bars of the
first pair are caused to separate and relieve pressure on the
workpiece and to make a return stroke during the forward stroke of
the second pair. Similarly, the second pair of bars makes a return
stroke during the forward stroke of the first pair. Apparatus of
this type is set forth in the Maurer Pat. No. 2,340,607 wherein the
bars are driven in the forward stroke by friction drive rollers and
are released by the rollers at a flat spot thereon for a return
stroke under the influence of a retracting spring. Another
continuous press of this type is disclosed in the Maurer Pat. No.
2,289,022 wherein selected bars from the upper and lower set of
bars are moved toward each other for compressing the workpiece
therebetween by means of a cam and follower arrangement and the
same bars are moved in a forward and return stroke on a common
carriage which is actuated by a separate cam and follower
arrangement. A difficulty with the apparatus of the former Maurer
patent is the use of the friction drive for advancing the bars; a
difficulty with the apparatus of the latter Maurer patent is that
it requires separate drive means for closing the press bars and
separate drive means for the feed or advance of the press bars.
Another prior art apparatus using the reciprocating bar arrangement
is shown in the Guyer Pat. No. 3,577,304. In the apparatus of this
patent, a pair of opposed lifter bars are spaced apart to accept
the workpiece therebetween and are mounted upon oppositely rotating
eccentrics. Upon each rotation of the eccentrics the lifter bars
successively compress the workpiece therebetween and impart a
forward motion to it; at the end of the forward stroke the lifter
bars open and a pair of holding bars are closed thereagainst by
spring pressure to maintain compression of the workpiece in a
dwell-condition while the lifter bars make a return stroke. A
disadvantage of this arrangement is that the workpiece is
intermittently advanced through the press and the pressure on the
workpiece is alternately applied by the eccentric-actuated lifter
bars and the spring-actuated holding bars.
Another type of continuous press utilizes sliding friction to
obtain a large bearing area for support of the moving press
members. In this type of apparatus a pair of endless belts are
disposed opposite each other and each is mounted on suitable drive
rollers. The portions of the endless belts which are disposed in
opposition and which receive the workpiece therebetween are
respectively backed by rigid plates which in turn are supported by
hydraulic plungers. To reduce the sliding friction the sheet of
material having a low coefficient of friction is interposed between
the moving belts and the respective backing plates. A continuous
press of this type is shown in the Pfeiffer Pat. No. 3,680,476.
SUMMARY OF THE INVENTION
According to this invention there is provided a continuous press
which is capable of applying high pressure to a workpiece while the
workpiece is continuously conveyed through the press. This is
accomplished by opposed platens each of which carries a set of
rails which face in a direction toward each other and which are
spaced apart to accept the workpiece therebetween. The rails of
each set are mounted on the respective platens with two rails being
mounted upon cams rotatably supported on the platen. Drive means
are provided for rotating the cams to impart orbital motion to the
rails; the cams being rotated in predetermined phase relationship
so that a pair of rails, one from each set, move simultaneously in
the respective orbital paths toward the workpiece to press it
therebetween and also move in the feeding direction to advance the
workpiece through the press. Additionally, the drive means imparts
orbital motion to a second pair of rails in such phase relation
with each other and the first pair of rails so that the second pair
are simultaneously moving away from the workpiece and opposite the
feeding direction while the rails of the first pair are in their
pressing-forward stroke. In other words, a first pair of rails, one
from each set, makes a press and advance stroke while another pair
of rails, one from each set, makes a release and return stroke.
Accordingly, the workpiece is continuously pressed and continuously
advances through the press.
Further, in accordance with the invention, the pressure applied to
the workpiece is maintained substantially constant as a function of
time when the workpiece is fed through the press. This is
accomplished by using an hydraulic force applying means for
supporting one of the platens. The other platen may be fixedly
mounted to the frame of the press. The hydraulic force applying
means is provided with an hydraulic accumulator which serves to
maintain a constant hydraulic pressure in the force applying means
despite the small cyclical variation in the spacing between pairs
of rails during the press-advance stroke of each pair. Further,
according to the invention, the pressure applied to the workpiece
is maintained at a uniform value over the surface of the workpiece.
This is accomplished by means of a "caterpillar" belt or endless
belt of crossbars. Such a caterpillar belt encircles the first
platen and extends over the rails thereon with the crossbars
spanning the rails, so that the force exerted by one or more rails
toward the workpiece is applied through the bars to the workpiece.
Similarly, such a belt encircles the other platen and coacts with
the rails thereof in the same manner. Additionally, it is preferred
to provide an endless sheet belt encircling the caterpillar belt on
the first platen and an endless sheet belt encircling the
caterpillar belt on the second platen, in order to present an
uninterrupted flat surface to both sides of the workpiece.
Also, according to the invention, a continuous press is provided
which has an exceedingly large load or pressure capacity. This is
accomplished by providing a large bearing area by mounting the
rails directly on the motion imparting cams or eccentrics, so that
each mounting constitutes a journal bearing. This bearing area is
multiplied by using multiple cams for each rail. Also the cam shaft
bearing area is maximized by spacing the rails and disposing a cam
shaft bearing between rails. In order to avoid gaps between the
rails each rail is preferably of T-shaped cross-section, i.e., the
head of the rail is wider than the web.
Further, in accordance with the invention, the variation in torque
requirements for driving the motion imparting cams is minimized.
This is accomplished by means of a polyphase arrangement of the
cams and rails. In one embodiment the rails of each set are divided
into two groups with all rails in the same group being moved in
their respective orbital paths in phase with each other. The motion
of the first group of rails is 180.degree. out of phase with the
motion of the other group of rails. This embodiment with two groups
of rails in each set, and with the motion of the two groups of
rails being of opposite phase, is referred hereinafter to a
"two-phase" arrangement. In another preferred polyphase arrangement
the rails of each set are divided into three groups and the orbital
motions of the three groups are displaced in phase from each other
by 120.degree.. In this arrangement which will be termed herein a
"three-phase" arrangement, the motion of the second group of rails
lags the motion of the first group of rails by 120.degree. and the
motion of the third group of rails lags the motion of the second
group of rails by 120.degree.. The invention contemplates, in
general, a polyphase arrangement of any desired number of phases
wherein the phase angle between successive phases is equal to
360.degree. divided by the number of phases or groups of rails.
Further, in accordance with the invention, the continuous press is
adapted to provide variable feedrate without changing the pressure
exerted by the press. This is accomplished by use of a common drive
for all of the cams which in turn actuate the rails through both
the pressure and advance strokes. Further, the synchronism of all
cams is assured by providing a gear drive from the common drive
means.
DETAILED DESCRIPTION
A more complete understanding of this invention may be obtained
from the detailed description which follows, taken with the
accompanying drawings in which:
FIG. 1 is a side elevation view of the continuous press of this
invention;
FIG. 2 is a view taken on lines 2--2 of FIG. 1;
FIG. 3 is a view taken on lines 3--3 of FIG. 2;
FIG. 4 is a view taken on lines 4--4 of FIG. 1;
FIG. 5 shows a detail of construction;
FIG. 6 shows a temperature control system; and
FIGS. 7 and 8 show a modification.
Referring now to the drawings, there is shown an illustrative
embodiment of the invention in a continuous press which is adapted
for simultaneously pressing and conveying a workpiece on a
continuous through-put basis while maintaining the workpiece at a
desired temperature during its travel through the press. It will be
appreciated as the description proceeds that the invention may be
embodied in a continuous press for a wide variety of applications.
Although the inventive apparatus is capable of producing extremely
high pressures on the workpiece, it may also be used in
applications where low pressure is required; further, whatever the
pressure requirement may be, the continuous press also provides
dimensional control for the workpiece. Additionally, the continuous
press is adapted to provide heat treatment or curing of the
workpiece by temperature control for a predetermined period during
the travel of the workpiece through the press. Typical applications
of the continuous press include the manufacture of large plywood
sheets on a continuous basis where the workpiece is relatively
thick and wide and moderately high pressure is required, together
with elevated temperature for curing. A typical application for a
small workpiece is that of manufacturing phenolic circuit boards
which require extremely high pressures and precise thickness
control.
As shown in FIG. 1, the continuous press comprises a stationary
base 6 which supports an upper press member 8 and a lower press
member 12. The upper press member is held in fixed position
relative to the base member 6, while the lower press member is
supported upon a vertically movable platform 16. An upper platen 10
carries an upper set of presser-conveyor rails 18 and a lower
platen 14 carries a lower set of presserconveyor rails 20. The
upper and lower sets of rails are disposed in face to face
relationship and are spaced apart to accept a workpiece 22
therebetween. It is noted that the workpiece 22 takes the form of a
continuous thin and wide board, such as plywood, which is moved
continuously through the press in the direction indicated by the
arrow.
Referring further to FIG. 1, the upper press member 8 is supported
on the base 6 by means of columns or corner posts 24 and horizontal
beams 26 supported on the posts. The platen 10 is supported from
the beams 26 by means of plural frame members 28 which are
partially concealed by the cover plates 30 and 32. A shield member
34, partially broken away in FIG. 1, is mounted on the platen 10
outboard of the set of rails 18 on the near side of the press as
viewed in FIG. 1.
The upper press member 8 also includes an endless caterpillar belt
36 which encircles the upper platen 10 and is supported upon a pair
of rollers 38 and 40, which in turn are supported on bearing plates
42 and 44, which depend from the beams 26. The caterpillar belt 36
comprises a multiplicity of rigid bar links, each of which extends
transversely of the press and spans the upper set of rails 18 in
engagement therewith. The bar links 46 are disposed edge-to-edge
and each is provided with a tapered cross-section to provide
clearance from the adjacent bar links in passing over the rollers
38 and 40. Each bar link is secured to the adjacent one by means of
a coil spring 48.sup.1 which draws the adjacent links together to
provide a substantially uninterrupted surface. (See FIG. 3 which
shows the lower caterpillar belt of the same construction).
Referring further to the upper press member 8, an endless sheet
belt 50 is disposed over the caterpillar belt 36 to provide a
continuous and smooth facing to be presented to the workpiece. The
sheet belt 50 is suitably constructed of stainless steel having a
smooth and polished outer surface which engages the upper surface
of the workpiece. The caterpillar belt 36, and consequently the
sheet belt 50, are driven on the rollers 38 and 40 by the upper set
of presser-conveyor bars 18 which, along with the associated
actuating mechanism, will be described subsequently.
Referring further to FIG. 1, the lower press member 12 will now be
described. This press member, in addition to the lower platen 14,
and the lower set of presser-conveyor bars 20 comprises an endless
caterpillar belt or link belt 52. The caterpillar belt 52 encircles
the lower platen 14 and is supported upon a pair of rollers 54 and
56. The rollers are supported upon bearing plates 58 and 60 which
are mounted upon the platform 16. The lower platen 14 is fixedly
mounted upon the platform 16 by frame members which are concealed
by the cover plate 62. The caterpillar belt 52 is of the same
construction as the previously described caterpillar belt 36 and
has its surface disposed in engagement with the lower set of
presser-conveyor bars 20. An endless sheet belt 64 encircles the
caterpillar belt 52 and is supported upon a pair of rollers 66 and
68. The rollers 66 and 68 are mounted upon bearing plates 70 and 72
respectively, which in turn are mounted upon the platform 16. The
endless sheet belt 64 is of the same construction as the sheet belt
50 described above, and presents a smooth polished surface to the
lower surface of the workpiece 22. The sheet belt 64 is longer than
the sheet belt 50 and is supported on the separate rollers 66 and
68 to provide a lower workpiece support surface at the input and
output ends of the press to facilitate loading and unloading.
The spacing of the press members will, of course, determine the
opening or vertical dimension of the press throat which is defined
by the spacing between the sheet belt 50 and the sheet belt 64 at
the opposed sets of rails 18 and 20. The throat or press opening is
preset in accordance with the desired dimension of the workpiece
and the setting is accomplished by raising or lowering the platform
16. For this purpose the platform 16 is mounted upon the base 6 by
plural hydraulic actuators or jacks 74, 76 and 78. The hydraulic
actuators are energized with hydraulic fluid from a pump 80 which
is driven by an electric motor 82. In order to supply substantially
constant pressure to the actuators despite minor fluctuations in
loading, an hydraulic accumulator 84, suitably of the bladder type,
is connected serially in the supply line 86 to the actuators which
are connected in parallel. The hydraulic actuators are provided
with double-acting pistons and a return line is connected with the
pump.
Referring now to FIGS. 2, 3 and 4, the upper and lower platens 10
and 14 and the upper and lower sets of rails 18 and 20 and the
associated actuating mechanism will now be described. The lower
platen 14, suitably in the form of a flat plate, is fixedly mounted
upon the platform 16 by frame members as previously mentioned. The
platen 14 supports the lower set of presser-conveyor rails 20. All
of the rails in the lower set are of the same construction,
suitably of steel, and have a T-shaped cross-section. Each of the
rails 20 has a web 90 which is narrower than the head 92 of the
rail. Additionally, each of the rails is provided with a fluid
passage 94 in the head of the rail for purposes which will be
described later. As shown in FIG. 3, each of the rails 20 is
provided with multiple axially spaced bearing surfaces 96. These
bearing surfaces are suitably provided by slots formed in the lower
edge of the web 90 of the rail; alternatively, however, the
surfaces 96 could be formed by holes drilled through the web of the
rail and, if desired, provided with suitable bearing inserts.
In order to support the individual rails 20 of the lower set of
rails on the lower platen 14 and to impart orbital motion to the
individual rails, plural cams are interposed between each rail and
the platen. In the embodiment of FIGS. 2, 3 and 4, a two-phase cam
arrangement is employed. In order to impart two-phase orbital
motion to the presser-conveyor rails the set of rails is divided
into two groups with each rail in the first group designated by the
reference character 20 and each rail in the second group designated
by the reference charater 20'. Each rail is supported upon plural
cams with the first group of rails 20 being supported upon cams 98
and the second group of rails 20' being supported upon a second
group of cams 98'. All of the cams 98 and 98' which are axially
aligned, such as those depicted in FIG. 2, will be referred to as a
set of cams and are mounted in fixed angular relation upon a cam
shaft 100 for rotation therewith. The set of cams depicted in FIG.
2 are mounted upon the cam shaft 100, while additional set of cams
98 and 98' are mounted upon additional cam shafts 100a, 100b, 100c,
100d, 100e, and so on, depending upon the desired number of sets of
cams (see FIG. 4). The cam shaft 100 is supported on the platen 14
by a pair of main journal bearings 101 and 103 and by a plurality
of intermediate journal bearings 105. It is noted that an
intermediate journal bearing 105 may be disposed between each pair
of rails to provide an extensive bearing area for the cam
shaft.
As stated previously, the cams 98 and 98' are preferably of the
same configuration, namely, circular eccentric of the same size and
of the same eccentricity, i.e. the same throw. As can be seen from
FIGS. 2 and 4, the cams 98 are 180.degree. out of phase with the
cams 98', i.e., they are displaced by a predetermined phase angle
of 180.degree.. Accordingly, in the positions shown in FIG. 2, the
rails 20 are in their most extended position in which the head of
the rail is displaced a maximum distance from the center of the cam
shaft 100 or the platen 14. At this given angular position of the
cam shaft 100 the rails 98' are in their most retracted position so
that the rail head is at its minimum distance from the center line
of the cam shaft or the platen 14. The difference between the
maximum and minimum displacements of the head of the rail is
referred to herein as the throw of the eccentric and is of course
equal to the displacement of the center line of the eccentric
itself from the center line of the cam shaft. It is noted that
rotation of the crankshaft 100 through an angular displacement of
180.degree. causes the rails 98 and 98' to reverse the positions
shown in FIG. 2. Rotation of the cam shaft 100 imparts orbital
motion to each of the rails 98 and 98' and, of course, a circular
orbital path is described by any given point on a rail for each
revolution of the cam shaft. It is further noted with reference to
FIG. 2, taking the angular position of the cam shaft 100, as shown,
to be the reference position, that 90.degree. rotation of the cam
shaft either clockwise to counterclockwise will change the
positions of both rails 98 and 98' so that they are at equal
displacements from the center line of the cam shaft, i.e., the
working faces 96 of the rails are in alignment with each other.
This relative position of the rails 98 and 98' may be referred to
as the transfer position because it is at this point in rotation of
the cam shaft that the rails 20 disengage the caterpillar belt 52
and the rails 20' engage the caterpillar belt 52, or vice versa,
and consequently the work applied to the workpiece is shifted from
one set of rails to the other. Further examination of the set of
rails 20 and 20' in FIGS. 2 will aid in further understanding of
the pressure and motion imparted by the presser-conveyor rails to
the workpiece. With the cam shaft 100 rotating in a clockwise
direction as viewed from the righthand end, the rail 20 will be
moving forward (direction of the arrow in FIG. 1 and into the paper
in FIG. 2), immediately after it passes its top dead center
position in the rotation of the cam shaft 100. This portion of the
orbital path of the rail 20 carries the caterpillar belt 52 in the
forward direction and hence advances the workpiece 22 through the
press. At the same time the rail 20' is disengaged from the
caterpillar belt 52 and immediately after passing its bottom dead
center position this rail is moving rearwardly (out of the paper in
FIG. 2) and upwardly. Accordingly the rotation of the cam shaft 100
in the clockwise direction as viewed from the righthand end in FIG.
2, continuously advances the workpiece through the press in the
feeding direction of the arrow shown in FIG. 1. The amount of
advancement of the workpiece for each revolution of the cam shaft
depends upon the throw of the cams or eccentrics and the forward
motion of the workpiece is substantially uniform.
Referring further to FIG. 2 the upper platen 10, the set of rails
18 and the associated actuating mechanism will now be described.
The assembly is basically the same as that just described with
reference to the lower platen 14 and the rails 20 and 20' and
accordingly only brief description is required. The set of rails
18, for convenience of description, is divided into a first group
including rails 18 and a second group including rails 18'. Each
individual rail is of the same construction as the rails 20 in the
lower set. Each rail is similarly mounted upon plural cams as
illustrated in FIG. 3 with respect to rails 20. Each rail 18 is
supported upon a cam (circular eccentric) 104 and each rail 18' is
supported upon a cam (circular eccentric) 104'. The set of cams
comprising cams 104 and 104' which are axially aligned with each
other are mounted upon a cam shaft 106 for rotation therewith. The
cam shaft 106 is supported on the platen 10 by a pair of main
journal bearings 107 and 108 and by a plurality of intermediate
journal bearings 109. It is noted that an intermediate journal
bearing 109 may be disposed between each pair of rails to provide
an extensive bearing area for the cam shaft.
Referring further to the cams 104 and 104', as shown in FIG. 2,
these cams are angularly displaced from each other on the cam shaft
by a phase angle of 180.degree.. Further, a phase relation is
pre-established between the first group of cams 104 and the first
group of cams 98 and hence between the first group of rails 18 and
the first group of rails 20. In this predetermined phase
relationship, as shown in FIG. 2, the motion of the rail 18 is
180.degree. out of phase with the motion of the rail 20. Similarly,
the motion of the rail 18' is 180.degree. out of phase with the
motion of the rail 20'. In other words, when rail 20 is in its top
dead center position the rail 18 is in its bottom dead center
position; also as shown, the rail 20' is in its bottom dead center
position while the rail 18' is in its top dead center position.
The coaction of the set of rails 20 and 20' with the set of rails
18 and 18' will now be appreciated. In order to advance the
workpiece 22 through the press the cam shaft 100 is rotated in a
clockwise direction as viewed from the righthand end in FIG. 2 and
the cam shaft 106 is rotated in a counter clockwise direction as
viewed from the righthand end in FIG. 2. During each revolution of
the cam shafts 100 and 106 the presser-conveyor rails 18 and 20
will move toward each other and in a forward direction, clamping
the workpiece therebetween and advancing it through the press. At
the same point where the rails 18 and 20 release the workpiece the
rails 18' and 20' will engage the workpiece in their motion toward
each other and in the forward direction, i.e., the transfer point
occurs where the work shifts from rails 18 and 20 to rails 18' and
20'. It is observed that in the circular orbital motion of the
rails 18 and 20 the components of motion toward and away from each
other is a harmonic motion with cyclical variation in the spacing
between the rails 18 and 20 at a frequency corresponding to the
speed of rotation of the cam shafts. Further, it is noted that when
the rail 20 is at its top dead center and the rail 18 is at its
bottom dead center, the rails are at minimum spacing and this
minimum spacing is less than the spacing at the transfer point when
the rails 18' and 20' engage the workpiece. Similarly, before the
next transfer point occurs the rails 18' and 20' will have passed
through their point of minimum spacing. As a consequence cyclical
variation in the spacing between the rails 18 and 20 and the
out-of-phase cyclical variations in the spacing between the rails
18' and 20', the pressure transmitted to the workpiece through the
caterpillar belts 36 and 52 is of an oscillatory character of very
small amplitude and having a frequency corresponding to twice the
rotational speed of the cam shafts. This cyclical variation in
pressure is eliminated by the action of the hydraulic accumulator
80 so that the pressure applied to the workpiece is substantially
constant in value.
In order to drive the cam shafts in synchronism and to maintain
proper phase relationship a drive train is provided as shown in
FIGS. 2 and 4. A single prime mover (not shown) is coupled to the
input shaft 110 and the prime mover is preferably of variable speed
type so that the feedrate of the press may be adjusted. The input
shaft 110 is coupled through beveled gears 112 and 114 to a splined
counter shaft 116 which is suitably journalled in the upper and
lower platens 10 and 14. The splined shaft arrangement accommodates
the change in spacing between the platens when the press is
adjusted for different size workpieces. The countershaft 116 is
coupled through beveled gears 118 and 120 to a stub shaft 122 which
is mounted in a bearing plate 124. A pinion gear 126 on the stub
shaft 122 meshes on one side with a driven gear 128 mounted on the
cam shaft 100. The pinion gear 126 meshes on the other side with a
driven gear 130 which is mounted on the cam shaft 100e.
In a similar manner, rotational drive is imparted to the plural cam
shafts mounted on the upper platen 10. This drive train is shown in
part on FIG. 2 with the counter shaft 116 connected through beveled
gears 134 and 136 to a stub shaft 138, which is mounted on a
bearing plate 140. The stub shaft is connected to a pinion gear and
a pair of driven gears on opposite sides thereof in the same manner
as the pinion gear 126 is connected to the driven gears 128 and
130, as shown in FIG. 4. Referring to FIG. 2, the aforementioned
pinion gear meshes with a driven gear 142 (which is one of the
aforementioned driven gears), which is drivingly connected to the
cam shaft 106. As previously explained, there are a plurality of
cam shafts mounted on the upper platen 10, but only one of these
cam shafts 106 is shown in the drawing, (see FIG. 2). The driving
arrangement for the plural cam shafts in the upper platen 10 is
exactly the same as the drive train for the plural cam shafts 100,
100a, 100b, etc. in the lower platen 14, which will now be
described further with reference to FIG. 4.
As shown in FIG. 4, and as previously described, the drive pinion
126 meshes with driven gears 128 and 130. With the input shaft 110
rotating clockwise, as viewed from the righthand end in FIG. 2, it
can be seen that the pinion gear 126 will be rotating clockwise as
viewed from the lower end in FIG. 4. Consequently driven gear 128
and the cam shaft 100 are rotated counterclockwise, as viewed from
the lower end. A drive gear 150 is keyed to the cam shaft 100 and
an idler gear 152 is mounted on the cam shaft 100 and rotatable
with respect thereto. In a similar fashion the cam shaft 100b
carries a driving gear 150b and an idler gear 152b. Similarly, on
cam shaft 100c, there is a driving gear 150c and an idler gear
152c. The other cam shafts also carry driving and idler gears but
before referring thereto it is noted that the cam shaft 100e is
also driven counterclockwise, as viewed from the lower end. The cam
shaft 100e carries a driving gear 150e and an idler gear 152e.
These driving and idler gears on cam shaft 100e mesh with idler and
driving gears 152d and 150d on the cam shaft 100d. Similarly, the
cam shaft 100f carries idler and driving gears which mesh with the
adjacent gears on cam shaft 100e. Thus, all of the cam shafts 100,
100a, 100b, etc. are driven in a counterclockwise direction viewed
from the lower end, which is the proper direction to advance the
workpiece through the press. It is noted that the cam shaft drive
arrangement just described permits a maximum number of cam shafts
to be mounted on the platen and hence a maximum bearing area for
support of the rails. The cam shaft drive arrangement for the cam
shafts on the upper platen 10 is identical to that just described
with reference to FIG. 4, it being understood, however, that the
cam shafts in the platen 10 are driven in the opposite direction
from those in the lower platen 14.
Referring now to FIG. 5, there is shown a detail of construction
which is employed in the embodiment depicted in FIG. 1. It is noted
that the rails 18 and 20, at the input end of the press, are formed
with divergent surfaces on the respective heads of the rails. This
construction provides a wider input area which facilitates the
entry of the leading end of the workpiece and causes compaction of
a bulky material over a desired distance of travel. Further, it is
noted in FIG. 5 that the set of rails 18 are provided with bearing
surfaces 96' similar to bearing surfaces 96, provided in the set of
rails 20. Since the rails 18 would tend to fall off the cams 104 in
the absence of a workpiece in the press, a retainer element 106 is
inserted in the opening in the rail above each cam.
Referring now to FIG. 6, a temperature regulating system is
illustrated for provided for either heating or cooling of the
workpiece during its travel through the press. FIG. 6 is a plan
view of the lower set of rails 20 and 20'. As previously noted,
each of the rails is provided with a fluid passage 94 in the head
of the rail (see FIG. 2). Such fluid passages are adapted for the
circulation of a heat exchange fluid, such as oil, through the
rails to maintain the rails at a desired temperature. The fluid
circulation system includes a source 160 of high temperature oil
which is connected by a supply conduit 162 to an inlet header 164.
The header 164 has a plurality of outlets, one for each rail, which
are connected respectively through flexible conduits 166 to the
passages in the rails. The outlet ends of the passages in the rails
are connected respectively through flexible conduits 168 to plural
inlets of an outlet header 170. A return conduit 172 is connected
between the header 170 and the return fitting of the source 160. In
a similar manner a source 174 of low temperature oil is connected
through a supply conduit 176 to the inlet header 164. The
circulation is completed through the passages in the rails to the
outlet header 170 and hence through a return conduit 178 to a
return fitting on the source 174. In order to selectively connect
either the heating fluid or the cooling fluid, control valves 180
and 182 are connected respectively with the sources 160 and 174.
The connection of the conduits to the rails is also illustrated in
part in FIG. 1. It is noted that the supply conduit 176 is provided
with a slip fitting 182 to accommodate the adjustment of the
position of the lower platen 14 relative to the base. Similarly,
the return conduit 178 is provided with a slip fitting 184. In the
like manner the supply conduit 162 and the return conduit 172 are
provided with slip fittings (not shown). A similar temperature
control system is provided for the rails 18 in the upper platen 10,
so that heat exchange means through the rails is provided on both
the upper and lower surfaces of the workpiece.
An additional embodiment of the invention is illustrated in FIGS. 7
and 8. In this embodiment a three-phase arrangement of the cams is
employed to realize certain advantages which will be discussed
subsequently. In the three-phase arrangement, the cams of a given
set of cams are divided into three groups, and the cams in each
group are displaced in phase from each other group by 120.degree..
This is illustrated in FIGS. 7 and 8, wherein a lower set of cams
200 includes a first cam 202, a second cam 204, and a third cam
206. Each of the cams is mounted on a cam shaft 208 for rotation
therewith. Preferably the cams are in the form of circular
eccentrics, as discussed with reference to the embodiment of FIGS.
1 and 2. As illustrated, the cam 202 is then at its top dead center
position while cam 204 is displaced 120.degree. clockwise therefrom
and cam 206 is displaced 120.degree. counterclockwise therefrom. As
shown in FIG. 8, the rails 210, 212 and 214 are supported
respectively on the cams 202, 204 and 206. With the cam 202 in its
top dead center position the rail 210 engages the caterpillar belt
216 while the rails 212 and 214 are in an intermediate position.
With the cam shaft rotating clockwise, as viewed from the righthand
end in FIG. 8, continued rotation from the position shown will
cause rail 210 to move forwardly and downwardly while rail 204 will
move further forwardly and downwardly and at the same time rail 214
will continue moving upwardly and forwardly. It is noted that rails
216 and 214 will reach the same height at 60.degree. displacement
after the top dead center position of rail 210. In the three-phase
arrangement the transfer points are separated by only 60.degree.
(as compared to 90.degree. for the two-phase). FIG. 7 also
illustrates the phase relation of the cams in the upper platen 10.
The cam 220 is in its bottom dead center position when the cam 202
is in its top dead center position. The cam 222 is displaced
120.degree. counterclockwise from the cam 220 and the cam 224 is
displaced 120.degree. clockwise from the cam 220. This set of cams
is mounted on a cam shaft 226 for rotation therewith. The cam shaft
226 is rotated in a direction opposite from the rotational
direction of the cam shaft 208; consequently, the cams 220 and 202
first move toward each other to clamp and advance the workpiece,
then the cams 206 and 224 move toward each other to clamp and
advance the workpiece, followed by the cams 222 and 204 which move
toward each other to clamp and advance the workpiece, the transfer
points being spaced at 60.degree..
The three-phase arrangement provides a significant advantage in
that the torque required to drive the press is caused to be more
uniform by reason of the fact that the transfer points are spaced
closer together in the angular displacement. Furthermore, the
amplitude of the cyclical pressure fluctuations (which are
eliminated by the hydraulic accumulator) are decreased relative to
the two-phase arrangement because there is smaller difference in
the minimum spacing between opposed cams and the spacing when the
opposed cams are at their transfer points. It will now be
appreciated that a multiple phase arrangement of higher order, such
as a six-phase, will lend further advantage in respect to the
above-mentioned operation.
In the operation of the continuous press the feedrate is suitably
established by adjusting the speed of the prime mover. Because of
the drive train previously described, synchronism and phase
relationships are inherently maintained and the pressure applied by
the press to the workpiece remains unaffected. It is noted that
feedrate is also affected by the throw or eccentricity of the cams
and for a given application the eccentricity and drive speed may be
correlated to obtain the desired feedrate.
The illustrative embodiment described herein is provided with a
substantially uniform gap through the press, as may be used for
plywood or the like. However, for certain applications involving
materials having a high bulk factor which are to be compressed, the
platens may be disposed at an angle so that the gap through the
press becomes progressively smaller as the material is thereby
gradually compacted.
Although the description of this invention has been given with
respect to a particular embodiment, it is not to be construed in a
limiting sense. Many variations and modifications will now occur to
those skilled in the art. For a definition of the invention
reference is made to the appended claims.
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