Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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1 BA(;KGROU~D OF T~IE INYENTION
This invention relates to the processing of logs by a saw mill and in
particular to a method and apparatus for processing the logs prior to their
being sent to the saw mill for cutting into commercial lumber.
Virtually all present day lumber mills operate on an in-line conveyor
belt basis. Logs are placed end to end on a conveyor belt. As a log is
trclnsported by the belt, it goes through a debarker, past saws where the
lot~ is cut into sections of desired length, and then is fed into a chipping
saw where the log is cut into slices of desired width. The logs carried by
O the conveyor belt are not r,ecessarily of approximately the same size.
Therefore, to process the logs with minimum waste, the chipping saw must
be adjusted for each log. If there is a great disparity in diameter of
' adjacent logs~ one log cannot enter the chipping saw until the preceding log
has completely passed through the saw and then the saw readjusted.
It is also a common practice for the trucks hauling the logs from the
forest to the mill yard to dump their loads of logs at selected locations
around the yard. No attempt is normally made to process the logs to any
extent until the logs are placed on a conveyor leading to ihe mill~ as
described above. Approximately 30% of the raw log materlal stored in a
i ~O typical yard does not end up as usable lumber, but is waste material of
various types. Compound;ng the above, the U.S. Forest Service has enacted
a requirement that all tree stems at least 2-1/2" in diameter and 5' long
must be removed from the forest. This adds to the amount of log material
that cannot be turned into usable lumber.
It would therefore appear desirable to sort the logs by size and type prior
to their entering the saw mill so that the processing efficiency is increased~
It would also be desirable to remove scrap and other non-usable logs from the
` system before enter;ng the saw mill.
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1 SUMMARY OF THE INVENTI0~1
In accordance with the principles of this invention, a method, and
apparatus operating in accordance therewith, is provided for processing logs
when first received into the mill yard. The logs are sorted by size and the
hard wood separated from the pine. Scrap materials are processed at this
time into material suitable for use by paper pulp mills or materials useful
for fuel. Accordingly, all of the stored logs are suitable for being sawed
into lumber and are grouped according to size and type, thereby permitting
logs of uniform size to be fed into the saw mill, increasing the mill's
ef~iciency.
The process is initiated by separating logs with greater than a pre-
determined diameter from logs with less than the predetermined diameter. The
larger diameter logs are sent down a first processing line where they are cut
to length and sorted as to type and size. The smaller diameter logs are
transFerred to a second processing line where they are cut to length and
:!~ sorted as to type and size, all logs of a smaller than predetermined diameter
passing down the second processing l;ne to a trash processing line. All scraps
from both the first and second processing lines, including bark and sawdust,
are also sent to the trash processing line. The trash processing line
converts the scrap and undersized logs into material suitable for Fuel and
~ paper pulp.
i DESCRIPTION OF THE DRAWI~G
The foregoing will be more readily apparent upon reading the following
description in conjunction with the drawing in which:
Figure l depicts a flow chart of a method tor processing logs in
accordance with the principles of this invention; and
Figures 2A - 2D, when arranged as shown in Figure 2, depict a schematic
plan view of apparatus operating in accordance with the method of the flow
c~art of Figure l.
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DESCRIPTION OF THE PREFERRED EMBODIMEN~
Referring now to Figure l, shown therein is a flow chart of the
method according to this invention. In the flow chart of F~gure l an open
arrow represents a transport step, an open circle an operation step, an
open triangle a storage step and an open square an inspec~ion step. Each of
these symbols contains therein a number, and the following Table I describes
the step associated with each of the numbered symbols.
TABLE I
, SYMBOL DESCRIPTION j SYMBOL DESCRIPTION
A Large log and mixed log Logs are inspected for size
/ 1 \ storage ~ and type
_ _
, ~ Logs enter system ~ First small log sort
'f First Separation Large hardwood stored
.,l5 ~fJ~ Logs smaller than 8" are Q Small hardwood stored
,~ ! ~ sent to small log side
_ . : -
,~ `1 ~ Large logs are sawed to ~ Second small log sort
~__J length and rejects removed
.
Cut to length large logs A Large pine stored
i, ~ are inspected for size and /13
' 20 type
:f First sort ~ Small pine stored
. ,~ Pine pulpwood size logs are ~ Rejects are removed
~' / 3 \ stored ~__J
:. _ _
~ 25 ~ lO" pine logs are stored ~ ,Rejects move to trash system
_ .
t ~ Second sort ~ Remaining srnall logs enter
~ ~_" ~ debarker
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,i l2" pine logs are stored ~ Trash system is separated
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I TABLE I (Continued)
: SYMBOL DESCRIPTION SYMBOL DESCRIPTION _
A 14" pine logs are stored All material less than 5"
. ~ ~ from trash system goes to
_
~' ~ Third sort ~ All material less than 5" is
~_ J blown to cars
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~, A Hardwood pulpwood size logs r~ ~ All material larger than 5"
/ 7\ are stored ~ re-enters small log system
_ __ _
A Scrap pine stored ~ Material from small log system
) / 8 \ ~ enters chipper
.~ ~ Fourth sort ~ Chipped material is stored
_
Q Hardwood saw logs are stored ~ Material from chipper is
i Q Hardwood scrap stored ~ Material larger than 5 re-
. L~,~' enters chipper
.. , Q Small log storage ~ Material less than 5" goes to
i Ll " " blower
Small logs enter small log ~ Material is blown to cars
~ ~ side of system .
.--. .
Cut-off saw cuts to length ~ Material goes to cars
Cut-off saw cuts to length ~ Material goes to cars
Scrap and pieces enter trash
system .
It is seen from the flow chart o~ Figure 1 and the descriptive material of
Table I that there are ~asically three processing lines according to the
. j principles-of this invention. The first processing line is for large logs~
.~ the second for small logs and the third a scrap processing line. The dividing
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1 point for large logs and small logs is illustratively eight inches; i.e.,
: ~ logs having a diameter less than eiyht inches are processed on the small log
line. These small logs may enter the system from either storage po;nts 1 or
2, whereas the large logs may only enter from storage point 1. The mixed
lt~gs at storage 1 are transported to the system at transport step 1. Operation
step 1 separates the mixed group of logs, the logs having diameters less than
eight inches being transported at transport step 3 to the small log processing
line, where they join up with the logs transported to the small log processing
line at transport step 2 from storage point 2. Continuing down the large
log processing line, at operation step 2 the large logs are sawed to length
and the rejects such as short sections of those logs or rotten logs are
transported at transport step 4 to the trash processing system. At this point
the cut lengths of large logs are ready for sorting and storing. At inspection
step 1, the logs are inspected for sorting as to for example, size and type.
At operation step 3 the logs are sorted and storage step 3 stores pine pulp
wood size logs and storage step 4 stores 10'1 pine logs. The second sort
.~ is at operat;on step 4, storage step 5 stor;ng 12" p;ne logs and storage
5~ step 6 storing 14" pine logs. The third sort takes place at operation step 5
~ where storage step 7 stores hardwood pulpwood logs and storage step 8 stores
.~ 70 scrap pine. The fourth sort takes place at operation step 6 where storage
step 9 stores hardwood saw logs and storage step 10 stores hardwood scraps.
~ It is understood that the particular sorts described above are for illustrative
$.~ purp~ses only. Different sorts may be performed depending upon`the desired
application, It is also understood that more or less sorting steps may be
~ ~S provided.
`~ The small log processing line begins with operation steps 7 and 8 where
cut-off saws cut the small diameter logs to the desired length. Scrap and
¦ short piec nter the trash proce sing system at transport step 4, After
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1 the logs are cut, at inspection step 2 the lo~s are inspected -for size and
type. Operation step 9 is the first small log sorting step where storage
sl;ep 11 stores the larger hardwood and storage step 12 stores the smaller
hardwood Operation step 10 is the second srnall log sorting step where
storage step 13 stores the larger pine and storage step 14 stores the
smaller pine. Any small logs which have not been previously rejected but do
not fit into any of the above categories enter the trash system. At operation
step 11, rejects go to the trash system via transport step 5 and undersized
logs too small for lumber enter the debarker at operation step 12 for processinginto paper pulp material. In the trash system, at operation step 13 the
trash material is separated, with material less than 5" in size going to the
blower v;a transport step 6 and material larger than 5" re-entering the
small log system via transport step 7. At operation step 15, material from
the small log processing system is chipped, the chipped material being stored
'- 15 at storage step 15. The stored chipped material is then separated at operation
. step 14 with material larger than 5" re-entering the chipper at transport
step 9 and material less than 5" going to the blower at transport step 8. At
operation s~ep 16 the trash material less than 5" is blown to cars at
transport step 10, and material from the chipper is blown to cars at operation
~20 step 17 and transport step 11.
Referring now to Figures 2A through 2D, the operation of apparatus to
perform the method heretofore discussed will now be described. When logs are
delivered to the mill, they may all be deposited directly on infeed deck 200.
However, if the logs are all of the smaller size, such as less than 8l' in
,5 diameter, they may all be deposited on deck 205. Loader 210 is utilized to
place the logs from infeed deck 200 one by one in end to end relationship on
~, cut-off saw infeed conveyor 21`5. The logs then travel to conveyor 220.
~ Conveyor Z is a dump conveyor illustratively of the type described in
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co-pending application Serial ~lo , entitled "Log Sorting Conveyor",
assigned to the assignee of this invention filed on even date herewith. Logs
of the smaller diameter are then dumped by dump conveyor 220 onto transfer
deck 225 while logs of the larger diameter travel to cut-off saw 230 where
they are cut to desired lengths. The cut logs then travel to cut-off saw
outfeed conveyor 235. Any scrap materials, such as short sections or rotten
logs9 are pushed from conveyor 235 by log kicker 240 onto reject slide 2q5
and then to conveyor 250.
The logs on conveyor 235 pass between the two booths of operator house
255. At this point the logs are scanned either by an operator or by commer-
cially available equipment which electronically scans logs to determine
their size. The logs then pass down the line of sort conveyors 260, 265, 270
and 275, which illustratively are dump conveyors of the aforementioned type.
When a log reaches the point at which it is to be temporarily stored9 the
operator operates a s~rt conveyor to dump the log dnto the appropriate stack.
For example, conveyor 260 corresponds to sort operation 3, conveyor 265 to
sort operation 4~ conveyor 270 to sort operation 5 and conveyor 275 to sort
operation 6. Bin 280 then corresponds to storage operation 3, bin 285 to
storage operation 4, etc.
The logs-on infeed deck 205 and transfer deck 225 are picked up by loader
300 one by one and are placed in end to end relationship on conveyor 305. The
logs then travel on conveyor 310 and conveyor 315 past two saws 320 and 325.
Saws 320 and 325 are positioned eight feet apart. A stop is provided on
conveyor 315 which will halt the movement of the log at a point either eight
feet or ten feet from saw 325. Thus, when saws 320 and 325 are simultaneously
operated/ either two eight-foot sections of log will be provided or one eight-
foot section and one ten-foot section are provided. The cut sections of log
th~n pa through operator ho_se 326 where an operator sorts the logs by means
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1 of dump c veyors 327 and 330 in the same manner as previously descriùed for
the large log processing line. Log sections of srnaller than usable diameter
:. pass onto conveyor 335, where reject sections which are not to be made into
paper pulp material are pushed by log kicker 340 onto reject slide 345 and
then to conveyor 350.
~: The trash processing system parallels the small log processing system.
. Conveyor 250, carrying rejected pieces from conveyor 235 is coupled to a bark
.~ vibrator conveyor, not shown, beneath and parallel to conveyor 315. This
bark vibrator conveyor continues below conveyors 325 and 330 and is coupled
to a bark vibrator conveyor 355 which moves the rejected pieces to conveyor
350. The material on conveyor 350 is fed to grizzly rolls 360. The small
pieces resulting from the action of grizzly rolls 360 fall to bark vibrator
conveyor 365, the larger pieces going to conveyor 370 via slide 375.
.. Meanwhile, the pieces on conveyor 335 transfer to conveyor 3~0 along which
they are transported to debarker 385. The debarked material then i~ transported
to bark vibrator conveyor 365. At this point, the large pieces of trash
.~. material are on conveyor 370 and the small pieces of trash material are on
conveyor 365. The material on conveyor 370 is transferred to conveyor 390
where it goes to chipper 395.
. 0 The material that goes to chipper 395 is broken down and blown into
:. cyclone 400 from which chips drop into chip surge bin 405. Chip surge bin 405
is a large container which acts as a buffer between chipper 395 and chip
screen 410, having an auger in its bottom to meter the chips onto chip screen
410, Chip screen 410 separates oYer-size chips, acceptable chips and small
. 5 particles If chipper 395 generated a large quantity of chipped material in
: a short period of time, this would be too much for chip screen 410 to
effectively separate. Therefore, the auger in chip surge bin 405 provides a
uniform f of chips to chip screen 4l0. The over-s;~e chips from chip screen
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1 ¦ 410 are ~eposited on conveyor 415 via slide 420 and are transported back to
chipper 395 for reprocessing. The acceptable chips from chip screen 410 are
¦ deposited on conveyor 425. The material on conveyor ~25 is of the proper size
¦ to be used for the manufacture of paper pulp. The small particles from chip
¦ screen 410 are deposited on bark vibrator conveyor 365. Bark vibrator
¦ conveyor 365 ~ransports the material thereon to conveyor ~30 which takes the
material to bark hog 435 where it is hogged into a material for a flash type
burning fuel and placed on conveyor 440, The material on conveyors ~25 and
l 440 are transported to respective blowers, not shownJ for blowing into
0 ¦ railroad cars, or the like, which are used to ~ransport the material to
suitable processing centers,
Several safety features to prevent machine damage are incorporated in
the trash processing system. F-stop 445 is a device that is operatively
connected to a demand meter on the motor that drives chipper 395. When a
large log starts into chipper 3957 the knives in the chipper are set to feed
the 1O9 into it. If a long log starts into chipper 395 and the chipper motor
becomes overloaded, conveyor 390 is automatically stopped and F-stop 445
comes down on the log to keep it from continuing to be fed into chipper 395.
Metal detector 450 is set so that when it detects metal in a piece of wood,
it stops conveyor 390 and activates F-stop 445. Magnets ~55, 460 and 465 pull
metal from material that is already chipped or hogged while allowing the
respective conveyors to run.
, It is thus evident that in accordance with the principles of this
invention, logs entering a mill may be sorted into groups which will enhance
the efficiency of the mill operation. In addition, preliminary processing of
- trash material, including bark and sawdust, results in commercially usable
products which may be sold.
Whereas this invention has been described with respect to an embodiment
thereof, it is understood that a person of skill in the art may make modifica-
t;ons ereto withou' departing from the sp;rit and scope of the invention.
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