Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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This invention relates to sawmill apparatus
which is particularly intended for use in feeding logs to
devices such as saws, canters or chipping heads operated
to cut along the length of the logs.
An efficient and now fairly widely used method
of cutting logs longitudinally is to feed them endwise to
the cutting device and to selectively adjust the device
towards and away from the longitudinal axis of each
passing log. This type of cutting results in a high rate
of production when the logs being processed are reaso-
nably straight and do not vary to any great extent in
diameter and so on. However, logs being used by sawmills
today will often vary in both diameter and taper and have
surface irregularities, all of which make it difficult to
support the logs properly as they are acted upon by the
cutting device.
The present invention contemplates conveying
apparatus which operates to feed a continuous flow of
endwise moving logs through saws or the like. Since logs
being processed in a sawmill often vary in size and
shape, the apparatus grips and supports the logs between
a firmly based chain and an opposing chain which can
yield to some extent and thus adapt itself to any minor
irregularities present on the log surfaces. Furthermore,
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the yieldable chain is equipped with spring flights which
provide a prcper grip on the log and the chain itself may
be supported in two sections each section adjustable
relative to the other to accommodate logs which may be
more misshapen than normal. However, for short logs one
section will suffice, with an infeed section stopping
approximately 5/8 of the log length past the last piece
of process equipment.
In the drawings:
Figure 1 is a side elevation of log conveying
apparatus constructed in accordance with the present
invention;
Figure 2 is a vertical section taken on the
line 2-2 of Figure l;
Figure 3 is an enlarged side elevation showing
a spring flight for a hold-down conveyor chain of the
apparatus;
Figure 4 is a detail of a modification of the
invention;
Figure 5 is a schematic view showing the
apparatus processing logs of varying diameter; and
figure 6 is another schematic view showing the
apparatus processing logs of irregular shape.
Referring to the drawings, the numeral 10 indi-
cates generally apparatus constructed in accordance with
the present invention. The apparatus 10 primarily is
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intended for use in cutting logs into cants, which is a
name commonly given to that portion of a log which
remains after slabs are removed from opposite sides of
the logs. A convenient way of processing the log to per-
form this slab removing operation is to move the log end-
wise past equipment such as twin or quad band saws or
twin or quad circular saws with or without chipping can-
ters and arranged to make simultaneous cuts lengthwise of
the moving log. It will be noted that some mills prefer
to chip away the side edge slabs using similarly arranged
chipping machines known to the industry as canters. The
saws or canters are spaced apart along the path of travel
of the log and associated with the piece of equipment is
a setworks which allows the cutting elements of the pro-
cessing equipment to be adjusted towards or away from the
longitudinal axis of the log, thus regulating the depth
of cut. The skilled man will appreciate that in the
illustrated embodiment the saws may be replaced by
canters.
The present apparatus is shown as comprising a
framework 12 which is erected on the floor 14 of a
sawmill. This open framework straddles twin band saws 16
which are arranged side by side in the manner best indi-
cated by dotted lines in Figure 2. A conventional main
~5 conveyor l of the present apparatus is also mounted on
the floor of the mill to extend longitudinally through
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the center ox the open framework. the conveyor indicated
generally at 18 has a single endless chain 19 trained
over sprockets 20 and 21 suitably mounted at opposite
ends of the framework. Other idler sprockets 22 and 23
are located below the floor 14 which has a slot 24
through which the chain extends. The upper run of the
chain is slidably supported on a bearer 25 which extends
longitudinally through the framework between the
sprockets 20 and 21. Log engaging teeth 26 are provided
on the chain 19 to grip a log seated on the upper run
which normally is in contact with substantially the
entire length of the log. The endless chain 19 is driven
by means generally indicated at 27, for example a
hydraulic motor, so that the upper run of the chain moves
in a direction of feed indicated by the arrow 28 which
appears in Figure 1, thus propelling the longitudinally
extending logs endwise up to and beyond the saws 16.
Logs are delivered to the conveyor 18 by being
moved endwise up to the intake end of the framework which
is on the right of Figure 1. The logs transferred on to
the upper run of the chain are moved between the
appropriately spaced saws 16 to the opposite or left end
of the conveyor where the cants are discharged. The
slabs cut from the sides of the logs by the saws drop
onto lateral conveyors 29 which operate to move the slabs
sideways clear of the framework to other discharge
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points.
The logs must be prevented from rolling
sideways off the single and longitudinally extending
chain 19 of the main conveyor and this is done by means
of a hold-down conveyor 30 which is located within the
framework 12 above the main conveyor. The conveyor 30 is
supported by a structure generally indicated at 32, this
structure being carried within the framework and
comprising an infeed frame 33 and an outfeed frame 34.
An endless chain 36 of the hold-down conveyor extends
around sprockets 37 and 38 journalled at oppositQ ends of
the support structure 32 above the corresponding
sprockets of the main conveyor. Relatively small
sprockets 39 and 40 also carried by opposite ends of the
structure 32 support the lower run of the chain 36 spaced
a suitable distance from and extending parallel to the
upper run of the main conveyor. Guide channels 42 and 43
are provided on the infeed and outfeed frames 33 and 34
respectively and the upper run of the chain 36 is sli-
~0 dably supported in these guide channels. Tension oE the
chain 36 is adjustable by means of a hydraulic take up
device 45 which is mounted on a bracket 46 projecting
from the infeed frame, the device carrying the sprocket
37. Device 45 need not be hydraulic. It can be operated
mechanically or pneumatically. Such tensioning devices
are well known. The hold-down conveyor is driven by
means generally indicated at 47 and preferably comprising
a hydraulic drive unit mounted on a bracket 48 which pro-
jects from the outfeed frame, the unit turning the
sprocket 38 to drive the lower run of the hold-down con-
veyor chain at the same speed and in the same direction
of travel as the upper run of the main conveyor Drive
means 47 may also be operated electrically or by any
similar conventional means.
The infeed frame 33 of the support structure is
movable between columns 50 provided on the sides of the
framework 12, see particularly Figure 2, these transver-
sely spaced columns being connected at the top by longi-
tudinal side members 51 as well as by txansverse members
52. At each pair of side members 50, the infeed frame
appears in cross section as shown in Figure 2 where
upright side members 54 of the frame will be seen to be
fitted with wear strips 55 which ensure easy sliding
movement of the frame on the columns 50. The guide chan-
nel 42 for the chain 36 is carried at the center of the
~0 frame 33 on a longitudinal member 56. A similar member
57 figure 1) on the outfeed frame carried the other side
channel 43 for the hold-down conveyor chain.
Longitudinal members 60 extend along the bottom
of the infeed frame, these parallel members being trans-
versely spaced apart and lined on their opposing faces
with wear strips Sl. Strips 61 are also transversely
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spaced apart and otherwise shaped to define a longitudi-
nally extending guide slot 62 open at the top and bottom
and provided with shoulders 63 about midway therebetween
as shown best in Figure 2. Other members 65, see
Figure 1, are carried by the outfeed frame to support
similar wear strips (not individually shown) defining an
extension of the guide slot 62 and the lower run of the
hold-down conveyor slidably extends through the longitu-
dinally aligned slots of the infeed and outfeed frames.
The outfeed frame 34 of the hold-down conveyor
is constructed in substantially the same manner as the
infeed frame and, in Figure 1, the spaced apart ends of
the guide channels 42 and 43 are shown downwardly turned
and spanned by the upper run of the hold-down conveyor
chain 36. The lower run of the chain 36 rides over a
bridge piece 67 which pivotally and extensibly connects
adjacent ends of the two longitudinally aligned guide
channels so that those ends can be disposed at different
levels if circumstances dictate.
The infeed frame 33 is adapted to be raised and
lowered by power devices generally indicated at 70. Each
of these devices comprises a hydraulic cylinder 72 which
is pivotally mounted as at 73 on the cross members 52 at
one end of the frame. The centrally disposed cylinder
has a piston rod 74 and a pivot connection 75 secures the
rod to the underside of a cross member 76 on the top oE
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the framework 12. The double acting cylinders 72, which
are located in the center of the infeed frame, are
included in a suitable hydraulic circuit indicated at 77
in Figure 1 only. The foregoing arrangement allows the
infeed frame which carried the hold-down conveyor to be
moved vertically as will be explained later but it should
be noted that the frame and conveyor are not required to
move up and down horizontally. In other words, the pivo-
tal connection provided for the device 70 allows the
infeed frame 33 to swing slightly on the framework and to
tilt so that one end of the hold-down conveyor can be at
a higher level than the opposite end of the conveyor.
The outfeed conveyor 34 is also provided with
power devices 78 which enable it to be moved up and down
as well as to swins within the framework. Since these
devices 78 are constructed and arranged as previously
described, no further explanation will be given although
the devices are also included in the hydraulic
circuit 77.
Referring now paxticularly to Figure 3, the
chain 36 of the hold-down conveyor will be seen to be
constructed of links 80 consisting of transversely spaced
side bars which are interconnected by countersunk rivets
81. Some of the links of the chain, for example every
fourth link, are replaced by a triangular lug 84 and,
secured to each lug by bolts 85, is a spring steel flight
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By which is inclined away from the direction of travel of
the chain links 80 at an angle of about 45~. The flights
have free ends 87 which are radiused as shown in Figure
3, that is, curved slightly towards the direction of tra-
vel of the chain links and the very tips of those free
ends are hollow ground to provide transversely spaced
prongs 88. This free end can be constructed with a
single point, or any other shape able to hold a loy by
digging into the log.
Referring again to Figure 2, the lower run of
the hold-down conveyor chain 36 will be seen partly
lodged in the guide slot 62 of the infeed frame. The
chain slides along the slot in contact with the shoulder
63 so that the lower run of the chain cannot move
downwardly below the position shown. At this time, the
spring flights 86 on the lower run project through the
slot 62 so that their tips are located above and in ver-
tical alignment with the upper run of the main conveyor
chain 19. In Figure 1, the flights 86 are shown pro-
~0 jecting away from the direction of feed indicated by the
arrow 28 with the free ends 87 curving slightly in the
opposite direction.
The above mentioned arrangement makes it
desirable to cushion the hold-down conveyor chain against
undue upward thrust which may be exerted by an unusually
distorted passing log and, in the present apparatus, this
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cushioning, if needed, may be done by means generally
indicated at 90. The cushioning means 90 is shown in
Figures 1 and 2 as comprising a number of air cylinders
92 which are spaced along the infeed frame 33 at suitable
intervals. Each cylinder 92 is pivotally connected as at
93 to the underside of the longitudinal member 56. The
cylinder slopes downwardly towards the infeed end of the
hold-down conveyor and a piston rod 94 of the cylinder i5
secured by a pivot pin 95 to a lever 96 which is also
secured by a pivot connection 97 to the member 56. Most
of the levers are fitted at their lower ends with pivo-
tally mounted shoes 100 which are shaped to loosely grip
and slidably support the top edge of the lower run of the
hold-down conveyor. Desirably, the two levers 96 nearest
the saw 16 are fitted with an elongated shoe 101 which
serves to hold the chain in reasonably close proximity to
the bridge piece 67 regardless of any difference in ele
vation between the infeed and outfeed frames.
The outfeed frame 34 may be cushioning or hold
down of the chain 36 and frames 33 and 34 can also be
achieved by a continuous strip of plastic polyethylene,
as shown in Figure 4. Such arrangement, which avoids the
necessity of cylinders 92, levers 96 and the attendant
hardware, includes a cover plate, for example of steel,
107 secured to the upper surfaces of member 60. A strip
108 of a low friction material, for example ultra high
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molecular weight polyethylene, is attended to cover plate
107 to contact chain 36.
As indicated a canter may be used in place of
saws 16 and a canter 109 is shown diagrammatically in
Figure 1. Another canter (not shown) will be opposed to
canter 109.
The present log conveying apparatus operates
effectively in processing a lineal flow of logs which can
be moving rapidly with only a short interval between the
ends of the logs. Preferably, the logs are scanned using
conventional scanning equipment which gathers the
necessary data regarding log diameter, taper, offset and
so on. This information is fed to a computer having a
memory bank in which information regarding appropriate
positioning of the frames 33 and 34 is stored. The com-
puter processes the information received and then signals
certain controls associated with the power devices 70 and
78 so that the hold-down conveyor frames are adjusted
automatically according to the size and shape of the log.
Other signals may be sent by the computer to the setworks
controlling the saws 16 or canters so that those saws may
be adjusted with regard to the transverse spacing between
their cutting blades.
In schematic Figure 5, the apparatus 10 is
illustrated as would appear when used to cut a run of
logs of varying diameter. Such logs are conveyed up to
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the apparatus and, while still a suitable distance away,
the logs are scanned and the infeed and outfeed frames
are adjusted vertically and tilted as required to receive
the leading end of the first log. The counter rotating
chains 19 and 36 are met by the log end so that the log
is centered over the main conveyor chain and the flights
86 swing down into clamping engagement with the top of
the log. As this occurs, the spring flights are flexed
slightly and the transversely spaced prongs 8B on the
tips of the flight dig into the log surface to some
extent thereby obtaining a firm grip. The chain 36 and
the flights 86, of course, are vertically aligned and are
centered along the length of the log which is moved in
the direction of feed or towards the twin band saws 16 or
canter lOg. The upper and lower runs of the two endless
chains pass between the transversely spaced saws or can-
ters 109 leaving all but the very center of the log clear
of the saw blades. This arrangement ensures that the log
is firmly gripped and held against rotation as the band
saws or canter act to remove the two side edge slabs
which will leave the cant suitably supported by the
outfeed end of the apparatus. The two frames supporting
the hold-down conveyor chain are raised and lowered auto-
matically as previously described and are tilted with
respect to the upper run of the main conveyor chain and
also with respect to one another if necessary to handle
the run of logs of varying diameter.
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Figure 6 is a schematic view showing logs being
processed which are about roughly the same diameter but
which have offset portions and are otherwise irregular in
shape, The apparatus can handle such logs as readily as
most other logs and operates in the previously described
manner to do so, that is, the infeed and ou~feed frames
are adjusted automatically to accommodate the rapidly
moving but irregularly shaped logs. If a bump on one log
exerts excessive upward pressure on the lower run of the
hold-down conveyor, the cushioning means 90 operates to
allow the chains to raise slightly and thus relieve the
strain which might otherwise be imposed on the spring
flights which still allows the flights to maintain a
proper grip on the top surface of the log.
The present invention provides an apparatus
that can feed a variety of logs to saws, canters, or
chipping heads without the necessity of frequent manual
adjustment or close supervision by an operator. The
arrangement of the flights of spring material mounted on
a conveyor, a vertically movable top chain guide, the
ability to move the top chain guide longitudinally of the
apparatus provides an apparatus in which the log is
restrained from moving sideways or from rotating while
moving longitudinally of the apparatus, including during
the cutting process. This accurate tracking of the log
through the apparatus maximizes recovery of available
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lumber and, furthermore, the apparatus of the present
invention does not requirP any premachining of the log to
achieve this result. The invention also provides a top
hold-down for the log that achieves rigid sideways sup-
port for optimum cutting accuracy and maximum recovery
and yet the support is narrow enough to pass through twin
cutting means, band saws or the like, spaced to cut one
board, flitch, cant or timber on edge.
