Note: Descriptions are shown in the official language in which they were submitted.
~7~
Backg'round and''Summary 'of''th'e In'vention
This invention pertains to log-handling apparatus,
and more particularly to a device which functions to separate
laterally fed logs for transmission endo, and one at a time,
to an off-bearing conveyor. While there may be many appli-
cations where such a separating device is useful, the device
disclosed herein will be described in the setting of a
sawmill, at a location just upstream from a log debarker.
In the usual sawmill, logs which are brought in
for cutting into lumber, are transferred from a log pond to
an endo-feea conveyor which is intended to transport them,
one at a time, into processing machinery such as a conventional
log debarker. Typically, logs which are furnished this
conveyor arrive side-by-side, and must be separated in some
suitable fashion so that only one log at a time arrives at
such machinery.
In the past, several kinds of lateral log separating
devices have been made available, which are intended to
accomplish the goal of one-by-one log feeding. For example,
two such de~ices are disclosed in U. S. Patents Nos. 3,502,1Yl
and 4,245,735, both issued to Antti Valo.
A general object of the present invention is to
provide an improved and unique lateral-transfer log-separating
apparatus which offers reliable separation of laterally
adjacent logs whose diameters fall within a predetermined
range of diameters, most critical condition is that encountered
where two successive side-by-side logs each has substantially
t'ne smallest diameter (3-1/2-inches herein) expected to be
encountered. The chord stretches referred to above which
form a critical element in the apparatus of the invention
are uniquely s',laped and oriented, as will be explained, to
assure positive separation under the critical operating
1:17~ 2
condition just described.
More specifically, the invention provides an apparatus
for transferring successive logs and the like, laterally, and
one at a time, between an intake station and a discharge station.
The apparatus has a long axis, and includes at least two
longitudinally displaced pairs of adjacent, operatively inter-
connected, reversibly and cyclically counter-rotative disks,
with the two disks in each pair having radially overlapping
peripheries, and being mounted for rotation about side-by-side
displaced, substantially parallel rotation axes, which axes are
substantially parallel both to the long axis and to the axes
of successive logs which are being transferred by the apparatus.
One disk in each pair is disposed adjacent the intake station,
the other being disposed adjacent the discharge station. The
one disk in each pair has a perimeter portion defined by plural
chord stretches including first, second, third and fourth
stretches extending, respectively, in all rotated positions for
the disk, generally from adjacent the intake station toward the
other disk in the pair. The first and second stretches and the
third and fourth stretches, respectively, join one another at
outwardly facing obtuse angles, and the second and third
stretches join one another at an outwardly facing reflex angle.
Simplicity in the construction of the apparatus of the
invention is contributed largely by the fact that all of the
operative log-separating discs just mentioned are carried for
counter-rotation on only two torque-tube shafts, which are
driven through the action of a common air-actuated cylinder.
These two shafts are supported on a simple common frame, and
are journaled for counter-rotation merely by two sets of end
bearings. One of the advantages of using torque-tube shafts,
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as just indicated, is that they can be made robust, and yet
light in weight so as not to be subject to bending. Further,
a two-shaft construction as outlined, obviates the necessity for
bearings intermediate the end bearings, and offers a structure
which is minimally subject to catching debris.
These and other objects and advantages which are attain-
ed by the invention will become more fully apparent as the
description which now follows is read in conjunction with the
accompanylng drawings.
Descrip*ion of the Drawings
Fig. 1 is a fragmentary top plan view of a log-
separating lateral-transfer apparatus constructed in accordance
with the present invention.
Fig. 2 is a view, on a larger scale than Fig. 1,
taken as if from the right end of Fig. 1, and rotated gao
clockwise to show the positional setting of the apparatus of
Fig. 1 relative to infeed and off-bearing conveyor mechanisms
in a sawmill -- all of that which is shown in Fig. 2 being
immediately upstream from a conventional log debarker.
Figs. 3 and 4 are on about the same scale as Fig.
2, are taken generally along the common view line 3-3, 4-4
in Fig. 1, and illustrate the two opposite extreme counter-
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and which, therefore, takes care of the problems heretofore
experienced with conventional separating apparatus.
Another object of the invention is to provide such
apparatus which is relatively simple and maintenance free in
construction.
Still another object of the invention is to provide
apparatus of the type just generally outlined, which can be
installed in existing sawmills as a ready replacement for
related prior-art apparatus, without the requirement for any
major mill modification.
According to a preferred embodiment of the invention,
the proposed apparatus includes, on a pair of side-by-side
displaced, substanitally parallel shafts, at least two
longitudinal].y displaced pairs of adjacent discs, which,
to~ether with their mounting shafts, are driven to perform
reversible cyclical counter-rotation, in plural ongoing
operating cycles which result in the one-by-one delivery, to
an off-bearing conveyor, of successive logs. The discs in
each pair are each formed with a uniquely configured perimeter
portion characterized by multiple angularly oriented chord
stretches which function, as will be described below, to
perform positive log separation.
While different mills may be set up to handle
different ranges of log diameters, the apparatus of the
invention, as described herein, has been de~signed to handle
logs whose diameters fall within the range from about 3-1/2-
inches to about 21-inches. Also, while different mills
might be intended for the handling of logs havi.ng different
maximum lengths~ the apparatus herein discussed is designed
to handle logs having lengths up to about 20-feet.
With respect to the capability of the instant
apparatus to perform positive log separation, probably the
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rotated relative positions for log-separating discs which
form part of tlle apparatus of the invention -- Fig. 3 showing
a pair of associated discs in fully closed conditions, and
Fig. 4 showing the same discs in fully opened conditions.
Fig. 5 is similar to Fig. 3, but is on a larger
scale, and depicts several different log-separating and
transfer operating conditions, including what might be
thought of as the extreme or critical operating conditions.
Figs. 6-13, inclusive, are schematic drawings, on
roughly the same scale as Figs. 2, 3 and 4, illustrating two
typical operating cylces for the apparatus of the invention.
Detailed Description of the Invention
Turning now to the drawings, and referring first
of all to Figs, 1 and 2, indicated generally at 20 is a log-
separating lateral-transfer apparatus which is constructed
in accordance with the present invention. In general terms,
apparatus 2U forms part of what might be thought of as the
infeed transport apparatus for logs which are being transferred
from the usual log pond (not shown) to a conventional rotating-
ring log debarker (also not shown). In the setting now
being described, logs, in any suitable fashion, are transferred
from the log pond mentioned to side-by-side laterally adjacent
positions on a lateral-transfer chain conveyor, such as the
one shown fragmentarily at 22 in Fig. 2. On this conveyor,
such logs travel toward apparatus 20, generally in the
direction of arrow 2~. Typically, the lateral travel speed
for logs on conveyor 22 is about 25-feet-per-minute.
1 ~ 7 ~ ~ ~ 2
Logs which are handled by apparatus 20 herein have diameters
which range from a minimum of about 3-1/2-inches to a
maximum of about 21-inches. Also, such logs have a typical
and maximum lengt'n of about 20-feet.
Logs on the chains in conveyor 22 are delivered by
gravity from the right end thereof in Fig. 2 onto a downwardly
s-lanted sheet-like apron 26 whose upwardly facing support
surface lies generally within the plane indicated by dash-
dot line 28 in Fig. 2. Plane 28 is normal to the plane of
Fig. 2. This support surface defines what is referred to
herein as an intake station 29 relative to apparatus 20, and
it is from this intake station that successive logs are
collected, as will be described, by apparatus 20.
As will be apparent, the long axes of logs received
in station 29 are substantially normal to the plane of Fig.
2, and substantially parallel to the longitudinal axis of
apparatus 20, which axis is shown generally at 30.
Shown to the right of apparatus 20 in Fig. 2 is an
off-bearing conveyor mechanism 32 having a frame 34 which
carries convergently slanted aprons 36, 38 that define a
trough 40 in the base of which travels a chain conveyor 42.
The upper run of conveyor 42 (the run visible in Fig. 2)
travels normal to the plane of, and away from the viewer in,
Fig. 2 along a transport axis shown generally at 44, which
axis is substantially parallel to previously mentioned axis
30.
The upper surface of apron 38 occupies a plane 46
which slopes downwardly progressing away from apparatus 20,
and which is substantially normal to the plane of Fig. 2.
The upper surface of this apron defines what is referred to
herein as a discharge station 48 relative to apparatus 20.
Logs which are received by conveyor mechanism 32 are transported
117~ 32
by chain conveyor 42 endo, and at a travel speed of about
200-feet-per-minute. These logs are fed directly to the
intake side of the log debarker mentioned earlier.
Considering now with somewhat greater detail the
construction of apparatus 20, and still referring particularly
to Figs. 1 and 2, the apparatus includes a frame 50 which is
formed, among other things, by a pair of longitudinal I-
beams 52, 54, to the tops of opposite ends of which are
joined, as by welding, a pair of transverse I-beams 56, 5~.
The long axis of this frame, which is also the long axis of
apparatus 20 has already been identified above at 30.
Mounted on the tops of beams 56, 5~, through
conventional roller bearings 60, 62, respectively, are
reduced-diameter opposite end portions of an elongated,
generally cylindrical shaft 54. Similarly, mounted on these
same two I-beams, through li~e roller bearings 66, 68, are
the reduced-diameter opposite end portions of a similar
elongated cylindrical shaft 70. Shafts 64, 70 are thus
journaled for rotation about their longitudinal axes which
are shown at 64_, 70a, respectively.
Shafts 64, 70 are operatively interconnected, and
are driven cyclically, in coordinated reversible counter-
rotative movements, by a drive mechanism generally indicated
at 72 in Fig. 1, which mechanism includes a conventional
double-acting pneumatic ram 74. Operation of mechanism 72
will be explained shortly.
Continuing with a description of apparatus 20 as
seen in Figs. 1 and 2, mounted, as will be explained, on the
outsides of shafts 64, 70, at plural longitudinally equidistance
stations along the shafts, are pairs of cooperatively associated
discs, including, in each pair, a disc, such as discs 76,
anchored as by welding to shaft 64, and a slightly longitudinally
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117~9~2
and 4-inches.
Each of discs 76 is mounted on shaft 64 with a
like angular orientation relative to the axis of the shaft.
This condition will be obvious fron Fig. 2 which depicts the
nearest one of discs 76 hiding all of the other similar
discs.
Focusing attention now on a disc 78 as depicted in
Fig. 2, the same has a perimetral outline which includes a
pair of generally diametrically opposed curved stretches
78a, 78b, '.~aving radii, respectively, of about 1-1/2-feet
and l-foot 2-1/2-inches, and subtending angles, respectively,
of about 90 and 70. Extending between the lower extremities
of stretches 78a, 78b in Fig. 2 is a straight chord stretch
78c which subtends an angle of about 110. Extending between
the upper extremities of curved stretches 78a, 78_ in Fig. 2
i8 a perimeter portion including plural chord stretches 78d,
78e, 78f, 78~. These four stretches are referred to herein,
respectively, as first, second, third and fourth chord
stretches. Stretches 78d, 78 and 78f, 78~ join one another
through radially outwardly facing obtuse angles of about
115 and 140, respectively, and stretches 78_, 78f join one
another through an outwardly facing reflex angle of about
200. Stretches 78d, 78_, 78f, 78~ have lengths, respectively,
of about 8-inches, l-foot l-inches, 3-inches and 2-1/2-
inches.
As was true with respect to the angular relationship
of discs 76 and the axis of shaft 64, discs 78 all have
substantially the same angular relationship relative to the
axis of shaft 70.
As will be more fully explained, discs 76, 78 in
Figs. 1 and 2 are shown in one limit counter-rotated condition,
which will be referred to herein as a closed condition for
3L~ 7~9~
the discs. In this condition, the adjacent perimeter portions
of discs 76, 78 in each associated pair of discs overlap one
another, as viewed along apparatus axis 30. And, as will be
apparent, the outer radial extent of chord stretch 76~ lies
along a circular path which substantially intersects the region
of joinder of chord stretches 78f, 78~.
Addressing attention now to Figs. 3 and 4 along
with Figs. 1 and 2, Fig. 3 is similar to the central portion
of Fig. 2 with respect to the relative positions shown for
discs 76, 78 therein. Still to be detailed in order to
complete a description of apparatus 20 is the structure of
drive mechanism 72, and this mechanism is best explained
with reference to Figs. 3 and 4 taken along with Fig. 1. In
particular, the butt end of the cylinder in ram 74 is
pivoted at 80 to a bracket 82 which is joined, as by welding,
to the inside face of the central flange in beam 54, near the
left end of the beam as seen in Fig. 1. The rod end of the
ram is pivoted at 84 to a double-arm crank 86 including arms
86a, 86b, which arms are welded to the outside of shaft 70
at the locations shown. Also welded to the outslde of shaft
70, in close proximity to crank 86, is another crank 88
which includes spaced arms 88a, 88b. The relative angular
orientation of cranks 86, 88 is clearly evident in Figs. 3
and 4.
Connecting crank 88 and shaft 64 are a link 90,
pivoted near one of its ends at 92 to the outer ends of arms
88a, 88b, and another double-arm crank 94 having spaced arms
94a, 94b, the outer ends of which are pivoted at 96 to the
other end of link 90.
In Fig. 3, ram 72 is shown in a fully extended
condition, with discs 76, 78 in their closed conditions.
With contraction of the ram, the cranks and link coact to
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adjust themsel~es toward the positions shown therefor in
Fig. 4, with resulting coordinated, simultaneous, opposite-
direction rotation of discs 76, 78 in clockwise and counter-
clockwise directions, respectively, as indicated by the
curved arrows in Fig. 4. The relative angular orientation
of the discs in Fig. 4 represents the opened condition for
the discs. It should be noted that with the discs in the
opened condition, chord stretches 76d in discs 76 are sub-
stantially copla~ar with previously mentioned plane 46, and
chord stretches 78d in discs 78 are substantially coplanar
with previously mentioned plane 28. In the normal operation
of apparatus 20, ram 74 is cycled repetitively between
extended and contracted conditions, with resultant reverse,
oscillatory motion produced in the discs to shift them
between the conditions depicted in Figs. 3 and 4. With the
two conveyor transport speeds mentioned herein earlier, a
typical cyclic rate for extension and contraction of ram 74
is about 15-cycles-per-minute.
Speaking in general terms about the operation of
apparatus 20, it should at this point be intuitively obvious
that, as the discs in apparatus 20 are shifted recurrently
between their opened and closed conditions, successive logs,
and occasionally successive groups of logs, are collected
from intake station 29 for ultimate delivery to discharge
station 48. As has been stressed herein earlier, it is
intended that, in the process of log transfer between
station 29 and station 48, the logs be separated positively
so that no more than one log at a time is delivered to the
discharge station, and fed onto the conveyor in mechanism
32.
A study of Fig. 5, along with the discussion now
to be presented, will help to explain several important
117~ 82
operating conditions for apparatus 20 during actual log-
handling situations. In this figure, discs 76, 78 are shown
in solid outline in what has been referred to as their
closed condition. In phantom lines in this same figure, the
same discs are shown in their so-called opened condition.
In the central portion of this figure, there appear several
circles depicted with different line qualities which have
been placed there to represent several interesting handling
conditions for logs having four different specific diameters
encompassed by the total range of log diameters intended to
be handled by apparatus 20. Similarly, appearing toward the
left side of t'ne figure, and again with different line
qualities, t'nere appear multiple circles which illustrate
different log-collection situations confronted by the apparatus
in the region of intake station 29.
Let us first examine the activity which occurs in
the central region of the apparatus, which activity is
critical to proper functioning of the apparatus in its role
as a log separator. Probably the most difficult handling
condition is that which occurs when two or more logs of
extremely small diameter have been collected by discs 78.
In Fig. 5 the two smallest-diameter circles, which are shown
in solid lines, represent idealized logs having the minimum
acceptable diameter of 3-1/2-inches. In this situation, it
is important that, with counter-rotation of the discs toward
their opened condition, only one of these two logs be
plucked from the central region for delivery to the discharge
station. Obviously, in the condition illustrated in Fig. 5,
this refers to the right-hand one of the two small-diameter
logs indicated. It should be apparent that an important
factor here to be considered is the construction of the
perimeter portions of discs 76. ~ore specifically, the
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117~39~3;2
structures of chord stretches 76f, 76~ here play a critical
role, And, it will be seen that the relative sizing and
angulation of these two chord stretches are such that, with
clockwise rotation of discs 76 from the position depicted in
Fig. 5, only the right-hand one of the two small-diameter
logs will in fact be removed from the center of the apparatus
and delivered to the discharge station. The other small-
diameter log will roll ultimately to the left along chord
stretches 78_, and bottom out in the region where these
chord stretches join with chord stretches 78d, as discs 78
rotate in a counterclockwise direction toward the opened
condition.
Repeated practice handling under the operating
condition just described has established a reliable history
of log separation under the most demanding of all separating
conditions. Such separation is accomplished predicta~ly
regardless, in almost all instances, of the shape of the
lo~, be it bowed, flared, twisted or deformed with projecting
bumps and branches.
Shown in dashed lines in the central portion of
Fig. 5 are two circles which represent the presence therein
of two 6-inch diameter logs. A quick mind's eye study of
what will happen with counter-rotation of the discs toward
the opened condition will indicate that, here also, positive
log separation will occur, with only the right-hand one of
these two logs in the figure being discharged to station 48.
In dash-dot lines in the center portion of Fig. 5,
there is shown an idealized 16-inch diameter log which rests
alone in the cradle defined between the discs. The axis of
this log is shown at 98, and it can be seen that this axis
is, from the point of view of the line of action of gravity,
located to the right of the outer radial extension of chord
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stretch 76~. Because of this situation, with counter-
rotation of the discs toward the opened condition, this 16-
inch log will be transferred to discharge station 48.
In dash-double-dot lines in the center of Fig. S
there is shown an idealized ~l-inch diameter log -- the
largest diameter log intended to be handled. The longitudinal
axis of this log is shown at 100, and, while positioned
slightly to the left of axis 98 as viewed in Fig. 5, is
nevertheless gravitationally to the right of the outer
extremity of chord stretch 76~. Thus, counter-rotation of
the discs will, here too, assure positive proper transfer of
thi~ log to the discharge station.
Turning attention now to the several situations,
vis-a-vis log collection, illustrated adjacent the left side
of Fig. 5, the four small-diameter circles which are shown
ln solid lines represent four idealized 3-1/2-inch diameter
logs resting on apron 26 in station 29 awaiting collection
under circumstances with the discs in apparatus 20 in the
conditions shown therefor in solid lines in Fig. 5. In this
waiking sltuation, the right-hand-most log is in contact
with the suraces of curved stretches 78a in discs 78, and
the other three logs abut one another progressing upwardly
along the apron, as shown.
With counter-rotation of the discs to the opened
condition (see the phantom lines in Fig. 5) these our logs
roll by gravity downwardly to positions where the two right-
hand-most logs are fully supported on chord stretches 78d,
the next uphill log straddles the gap ~etween discs 78 and
apron 26, and the fourth uphill log is fully supported still
on apron 26. This condition is illustrated in Fig. 5 with
the small-diameter logs depicted in dashed lines.
Then, with return counter-rotative movement of the
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1~7~S;2
discs toward their closed condition, only the right-hand two
logs will be collected by discs 78 -- the other two logs
being shifted slightly upwardly to remain on the apron in
the positions previously held by the two right-hand-most
logs in solid outline in Fig. 5. Such a log-collection
operation is one which would have lead to the separation
condition first described in connection with this figure
respecting the two small-diameter solid logs shown in the
center of the figure. It should be obvious to those now
reading this description that there are certainly other
kinds of collection conditions when plural logs can be
collected at once, but there will substantially never be a
condition when more than two logs -- those being of the
smallest expected diameter -- will be collected. And,
inasmuch as the challenge presented apparatus 20 to separate
two such small-diameter logs, simultaneously held in the
trough defined between the discs when closed, is the most
taxing situation, all other separations where more than one
log has been collected will take place readily.
Still with reference to the left side of Fig. 5,
shown in dash-dot lines are two larger-diameter circles
which represent two idealized 6-inch diameter logs in the
relative positions which they will occupy, if adjacent one
another, under a circumstance with the apparatus open, and
in a condition ready to collect a log. In this situation,
only the right-hand one of these two logs will be collected --
the left-hand log being shifted upwardly slightly along the
apron with clockwise rotation of discs 78.
In dash-double-dot lines and in dash-tripl~-dot
3~ lines in Fig. 5, there are shown idealized logs having
diameters of 16-inches and 21-inches, respectively, resting
on apron 26 and in contact with curved stretches 78_ in
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discs 78. ~t should be obvious what happens in the cases of
each of two such logs when the discs in apparatus 20 have
rotated to their opened condition. Namely, the single log
alone awaiting cvllection is all that will be collected.
Let us shift attention now to Figs. 6-13 inclusive
which, as mentioned earlier, depict two full operating
cycles of apparatus 20.
Starting with Fig. 6, discs 76, 78 are shown in
the opened condition and four logs of different diameters
are shown at 102, 104, 106, 108. Logs 102, 1~4 are of such
sizes that both will be collected simultaneously by the
apparatus. Fig. 7 depicts the end of the first next half-
cycle in the operation of apparatus 20, with the discs shown
in their closed conditions, and with both of logs lO~, 104
nestled in the trough defined by the discs. Logs 106, 108
remain on apron 26, in the positions shown.
Fig. 8 shows the condition of apparatus 20 part
way into the next half-cycle of operation, and illustrates
that separation has occured between logs 102, 104.
In Fig. 9, the discs are shown in the relative
positions which they have nearing the end of the first
complete cycle of operation, and it will be noted that log
10~ is discharging under the influence of gravity from the
apparatus into discharge station 48.
In Fig. 10, the apparatus has returned to the same
condition illustrated for it in Fig. 6, except, of course,
that the "log situation" has changed. More particularly,
log 102 has been transferred from the appa-fatus, log 106 has
been rolled into a position to be collected by the apparatus,
log 108 has moved downwardly on apron 26, and next-in-line
log llO has made its appearance on the apron.
In Fig. 11, we again see the discs in the apparatus
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Z
in their closed condition. Here, logs 106, 104 are nestled
in the trough formed between the discs, and logs 108, 110
have remained on apron 26.
Fig. 12, the relative positions of the discs is
the same as that shown in Fig. 8. Here, positive separation
has taken place between logs 104, 106.
Fig. 13, regarding the relative positions of
discs, is like Fig. 9, and here it will be seen that log 104
is dropping by gravity into discharge station 48.
The operation continues in this manner.
It should thus be apparent how all of the advantages
and objectives ascribed to the apparatus of the invention
are met in the construction which has just been shown and
described. Within the entire range of logs for which the
apparatus has been designed to operate, positive log separatiGn
for feedlng of logs one-by-one to an off-bearing conveyor
for endo transport is accomplished under all operating
conditions.
The proposed apparatus is extremely simple in
construction and highly maintenance free. Contributing in
an important manner to this aspect of the apparatus is the
fact that all of discs 78 are carried on a common shaft 64,
and all of discs 78 are carried on a like common shaft 70.
A single drive apparatus, coupled through suitable cranks
and a link, suffices to operate simultaneously both of these
shafts and their associated log-separating discs.
The teeth provided along chord stretches 76d, 76_
help to brake the travel of a heavy log falling into the
apparatus during a "collection" procedure.
A modification in the apparatus of the invention
which may be useful in certain applications, is the provision
of a curved "skin" in the form of sheet metal, secured as by
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welding to the outside surfaces 78a in disc 78. Such a skin
would be in the form, generally speaking, of a segment of
cylinder, and would act as a fender or bumper with respect
to logs in in~ake station 2g.
While a preferred embodiment of the invention has
been described herein, it is appreciated that other variations
and modifications may be made without departing from the
: spirit of the invention.
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