Note: Descriptions are shown in the official language in which they were submitted.
IMPROVED FLAIL MEMBER FOR DEBARKING TREE~
BACKGROUND OF THE INVENTION
The present invention relates generally to a method and
apparatus for debarking tree stems and more particularly to a debarking
process that utilizes the impact energy ïrom rotating chains or the like to
remove bark from the stems as they pass through the debarking station.
Typically tree stems are debarked before undergoing a subse-
quent conversion process whether it be to convert the tree into lumber
products, veneer for plywood manufacture, or chips Ior pulp manufacture.
In addition, when trees are cut ~rom the forest they are typically delimbed
to remove the limbs before further processingO Each of these steps
10 preliminary to the conversion process is time consuming and expensive. The
limbs and bark can be collected and used as fuel.
The prior art contains a number of dif~erent methods for both
debarking and delimbing. For example, when delimbing large trees, it is
common practice to employ workmen in the woods with chainsaws to simply
15 cut the limbs in the ~rest before the logs are hauled to the debarking site.
With large delimbed logs, debarking rnethods include high pressure water
jets, ring type debarkers where a rotating ring with knives scrapes the bark
from the tree, and other well known debarking processes.
Over the years greater quantities of smaller trees are being
20 harvested and converted into useful products. By smaller trees, it is meant
trees that are grown and harvested with smaller diameters. IUost of the
large old growth forests have been logged and many of the forest products
companies are now harvesting subsequent growth timber.
~or example, in the Midwest and southern growing regions of the
25 United States, many forest products companies are planting, growing and
harvesting trees in a cycle that utilizes extensive forest management
techniques and harvesting techniques that essentially treat the trees as an
agricultural crop. With this type of forest management, typically a
significantly larger number of trees are harvested from the same acre of
30 land and the harvested trees will be relatively smaller in diameter.
~onsequently, in order to maintain production at conversion facilities such
as sawmills, plywood plants and chipping facilities, new ways must be found
~$
to handle and prepare the trees for conversion. Of course, the ways
selected must be cost effecient, safe and suitable for the intended purpose.
Many ways have been disclosed for preparing large quantities of
small diameter trees for conversion. For example, it has been suggested
5 that a quantity of trees can be accumulated in bunches and then a chain flail
delimbing apparatus utilized to essentially knock the limbs off the trees
before they are transported to a debarking site. As with large diameter
trees, chain saws may be utilized to remove the limbs, although when
handling a large number of relatively small diameter ~rees, the cost
10 effectiveness of utilizing chain saws goes down. After the small diameter
trees are delimbed, then the debarking process must occur before subse-
quent conversion. Again, if relatively large diameter trees are to be
converted into, for example9 lumber products the tree stems will typically
be debarked utilizing a ring type debarker where R single log is longitud-
15 inally passed through the debarking station. While the bark is removed, theproduction rate is not high in relation to the total costs. When debarking
small diameter trees where the debarked trees will be converted into chips,
drum type debarkers have been utilized which process a large number of
tree stems in a rotating cylinder having means for mechanically removing
20 the bark primarily by a tumbling action. This debarking method also has
shortcomings in that the stems must remain in the drum for a long period to
remove the bark and as a consequence good wood can be damaged.
What is needed is a method and apparatus that is capable of
debarking large quantities of relatively small diameter tree length stems in
25 a substantially continuous rnanner while at the same time removing the
limbs and preferably converting the limbs and removed bark to fuel. Such a
system should be capable of accepting a plurality of substantially full length
trees with limbs in a side-by-side relationship for transport through a
debarking-delimbing station. At the debarking station, substantially all
30 limbs and bark are removed to a level where the debarked and delimbed
trees can be fed directly into a chipper. The bark and limbs are fed to a
conversion means where they are reduced to suitable siæe for use as fuel (so
called "hog fuel").
Preferably this system should be capable of being, in one forrn,
35 mobile so that it may be transported to a woods location where the
debarking-delimbing and chip conversion can take place. In another form it
may be of the stationary type typically located at a conversion facility. An
integrated debarking-delimbing system and, if desired7 with chipping and
fuel preparation apparatus means that several handling steps are eliminated
thereby reducing the overall cost of tree preparation for subsequent
conversion. If the system is utilized at a woods location, the output of the
system can be hauled from the woods in chip and/or fuel form, thereby
significantly reducing costs compared to moving whole trees before prepara-
tion. Also with such an integrated system, the initial capital investment for
meeting the general functional requirement of preparing trees for down-
10 stream conversion is significanly less.
As will become very clear to those skilled in the tree handling
and conversion art, the present invention will afford significant advantages
over state-of-the-art methods and apparatus. In addition, many useful
specific applications of the present invention will be apparent in addition to
15 those that are disclosed herein. It should be readily apparent that one cf the
primary uses of the method and apparatus will be as an economical
converson process for commercial thinnnings, which are those trees removed
from forests prior to a final commercial harvesting.
Accordingly a primary object of the present invention is the
20 economical debarking of relatively small trees.
Another object of the present invention is the provision of a
debarking system integrated with conversion means to reduce handling
cos ts.
Yet a further object of this invention is to provide a high
25 production debarking method meeting the standards for conversion to high
quality chips.
Yet another object of this invention is the provision of an
efficient high production debarking system that i9 relatively inexpensive to
build and operate.
Still a further object is the provision of a debarking system that
can be mobile or stationary depending upon user needs.
Yet a further object of this invention is the provision of a
debarking process that also adequately delimbs at high production rates.
Still anokher object of this invention is the provision of close
35 coupled means to convert the bark, limbs and foliage to usable material and
the debarked, delimbed trees to chips.
c~
Yet a further object of this invention is to provide a debarking
system that is substantially enclosed to reduce the risk of potential personal
injury or property damage.
Still a further object of this invention is the provision of suitable
material handling means to keep the flow of rnaterial within the system
smooth, uniform and consistent, thereby increasing output and reducing the
occurrences of downtime due to material backups.
These and many more objects of the present invention wiU
become apparent upon reading the specification to follow in conjunction
10 with the attached drawings.
SUMMARY OF THE INVENTION
Briefly stated the present invention is practiced in one form by
mounting a plurality of elongated chain sections on a rotatable drum in
substantially ~uliform rows. The improvement comprises at least some of
15 the chain sections having a lateral vibratory length less than the rernainingchain sections whereby the shorter chain sections are effective to remove
bark from a top or bottom surface of a traveling log while the longer chain
sections are effective to remove bark from the sides of a traveling log.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is an isometric view depicting a mobile version OI the
debarking apparatus.
Figure 2 is a side elevation view in cross section showing the
internal design of the debarking station.
Figure 3 is an isometric view showing the internal design of the
25 debarking station with sections partially cut away to show the size reduction station and transport means.
Figure 4 depicts a partial row of chain sections which comprises
one of the plurality of rows of chains mounted on a flail drum.
Figure 5 is a view similar to Figure 4 but depicts a row of chain
30 sections having an effective longer length than those depicted in Figure 4.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring first to Figure 1, a general description will be given of
the mobile version of the present invention. While a mobile version will be
described, those skilled in the art will appreciate that an alternative
35 implementation of the invention could be a stationary fixed system located
within a wood handling yard. The present invention, however, does have the
flexibility of being implemented in mobile form so that it can be transported
to woods locations where trees can be accumulated and processed quickly
and efficiently. The alternative use is where logs are accumulated in the
woods and transported to a central processing area typically called a wood
5 yard.
In the mobile version, the overall length, height and width
dimensions must be sized in order to make the unit transportable over
existing roads. Comprising the self-contained debarking system as depicted
in Figure 1 is a substantiaUy flat horizontally disposed frame indicated
10 generally at 10. Frame 10 is mounted on subframe structure 12 which in
turn accommodates a pair of laterally extending side-by-side axles 14 on
which wheels 16 are mounted. Wheels 16 are, of course, free to rotate and
support the back end of frame lû during transport. The back end of
frame 10 also has a rear bumper structure generally indicated at 1~. At the
~5 other end c-f frame 10, below the horizontal plane of frame 10 but connected
thereto is suitable structure for supporting the front end of the system for
transport. In effect, the wheel mounted horizontal frame 10 with all the
rest of the elements becomes a mobile trailer, transportable to an operating
site.
lIorizontal frame 10 also supports the functioning elements of
the debarking system including the infeed end generally indicated at 20, the
debarking station generally indicated at 22 and the outfeed end generally
indicated at 24. The infeed end at 20 accounts for approximately two-thirds
the overall length of frame 10 and consists of an infeed conveyor belt 26 or
25 other suitable conveying means e2~tending longitudinally between laterally
spaced side walls 28, 30. Side wa71s 28, 30 extend vertically above the
horizontal frame 10, to a height that will be approximately equivalent to the
dimension of the largest diameter tree to be processed. Side walls 28, 30
îunction to guide and constrain the movement of the trees to be processed
30 after they are placed onto the conveyor belt 26. Conveyor belt 26
terminates at the infeed opening, generally indicated at 32, to the debarking
station 22. The outfeed end 24 is comprised of, in the embodiment depicted,
a flat support surface 34 atop which the debarked stems will travel in a
downstream direction. The upper surface of the conveyor belt 26 and the
35 upper surface of flat plate 34 form the horizontal feed plane over which the
bottom most surfaces of the tree stems will travel. In order to provide a
positive outfeed drive means roUs could be employed although they are not
shown in the figures as could a bottom powered conveying surface.
The embodiment depicted in ~igure 1 during operation is
intended to be close coupled to a commercially available mechanical
5 chipping machine (not shown) so the stems as they are fed outwardly in the
downsteam direction from debarking station 22 can be fed directly into the
chipping means which will pull them away from the debarking system. While
a chipping station is not depicted in the figures, they are commercially
available from such manufacturers as Morbark. One with ordinary skill in
10 the tree processing arts will understand that a suitable commercially
available chipping system may be close coupled to the outfeed end 24 of the
debarking system and chips continuously produced as trees are fed through
debarking station 22. As will be further described later, the feed rates ~rill
be matched for efficient operation.
Serving to support the hori~ontal frame 10 at the proper vertical
height, the wheels 16 and subframe 12 will be mounted at the proper
vertical location and beneath the debarking station 22 a pair of laterally
spaced tubular mounted support plates each indicated at 36 serve to support
the other end of the frame at its proper vertical height. Control cylinders
20 each indicated at 38 can vary the height of horizontal îrame 10 with respect
to support plates 3B once they flre extended outwardly and positioned in
place. Functionally, support plates 36 are extendable laterally outwardly to
support the overall system. The plates 36 can either be pivotally or slidably
mounted within supporting frame work as will be obvious to one skilled in
25 the art.
The length and width of conveyor belt 26 is sufficient to
accommodate a plurality of full length tree stems disposed in a side-by-side
relationship for transport through the debarking station 22. Usually,
anywhere from two to five elongated stems will be placed on eonveyor belt
30 26 for conveying through the debarking station in the laterally spaced
orientation. This particular transport orientation for a plurality of
elongated stems is known and may, for e?~ample, be seen by referring to
issued U.S. Patent 4,214,616 issued July 29, 1980 to M. J. Brisson and
assigned to ~errano Limitee of Plessiville, Canada. While the Brisson patent
35 teaches side-by-side transport of long stems through a processing station, it is primarily intended for delimbing purposes compared to the present
invention which is primarily for debarking purposes. While full length tree
stems can be accommodated, shorter tree segments can also be processed.
Mounted on top of debarking station 22, which will be described
in detail shortly, is an operators cab 38 and articulated boom and grapple
5 assembly ~0. The cab and boom assembly is rotatably mounted on top of the
debarking station such that the operator can observe and control grapple
movement. These are also commonly used in the forest products industry
for picking up and handling elongated objects such as full length tree stems.
Typi~ally, the operator will have a pile of full length tree stems beside the
10 debarking system anci will manipulate the grapple and boom to pick up three
or four of the stems simultaneously for placing atop the conveyor belt 26.
While the present invention has been designed and is most effective in
removing bark from tree stems, it is also capable of removing branches and
limbs together with foliage. A handling and converting system is provided
15 for the bark, limbs and foliage to accumulate and reduce it in size and then
to clear it from the debarking station. These features will be explained
later.
In the self-contained mobile debarking system, a power plant is
provided indicated generally at ~2 to power the various operating
20 mechanismsO In the embodiment depicted the power plant is in an enclosure
44 which houses for example a diesel engine to provide both fluid pressure
and electrical power. Given the various operating elements of the present
invention, one having oldinary slcill in the art will be able to provide the
appropriate energy to the various drive means for the operating elements.
25 An access door 46 is provided on the enclosure ~4 to keep other unwanted
items out of the power plant. The enclosure should also serve to muffle the
sound generated by the power plant.
DETAILS OF DEBARKING STATION
At the infeed opening 32 of debarking station 22 a pair of
3n vertically spaced feed rolls may be seen by referring to Figures 2 and 3.
The lower feed roll 48 is fi2~ed in position and has a plurality of peripheral
teeth 50 the edges of which will, during operation, intersect the hori~ontal
feed plane thsreby contacting and pulling the elongated stems, each
indicated as 52, further into the debarking station. Feed roll ~8 is mounted
35 on a suitable rotatable drive shaft 54. The top feed roll 56 is larger in
diameter than roll 48 and is mounted within its supporting frame 58.
n~
Similarly to bottom roll 48 a plurality of peripheral teeth 60 are mounted on
the surface of roll 56 to engage the stems. The roll 56 is rotatably mounted
in laterally spaced bearings eacll indicated at 62 positioned within support
frame 58. Support frarne 58 is pivotally mounted on laterally spaced pivots
points 64. Support frame 58 is also an enclosure for top roll 56 and serves to
restrain flying debris.
As will be readily apparent to those skilled in the art, top roll 56
is pivotally mounted in order to accommodate various log sizes as they are
transported into the debarking station in the side~by~side relationship. It
10 has been found that approximately 3500 lbs of force is desirable to have
exerted by the top roll on the top surfaces of the traveling stems. With such
a force, positive feed is maintained and the stems are maintained in their
side-by-side relationship and in addition some limbs will be broken early and
will fall downwardly into the bottom of debarking station 22. Still referring
15 to Figure 2, the downstream end of conveyor belt 26 may be seen as being
spaced longitudinally from bottom roll 48. Conveyor belt 26 terminates in
the longitudinal direction by being trained about a guide roll 66 which can be
mounted for rotation in frame 10. A small tensioning roll 68 ~or belt 26 is
positioned longitudinally upstream from guide roll 66 and likewise may be
20 mounted within frame 10.
Serving to enclose and support the top and bottom flail members
70, 72 repectively is a structured enclosure consisting of upper laterally
extending front wall 74, an inclined upper front wall 76, a top substantially
horizontal wall 78, a back inclined wall 80 and a back substantially vertical
25 wall 82, together with laterally opposed side walls 84. The just described
walls form the top enclosure which also serves to support the t~p roll 56 and
the top flail member 70 for rotation therein. The top enclosure for
debarking station 22 as previously indicated can also serve to support the
cab 38 along with its boom and grapple assembly ~0. Consequently, if the
30 top enclosure must structurally support the weight of the cab and boom and
grapple assembly, it will necessarily need stiffening members and they can
easily be designed into the structure. Laterally spaced opposite one another
and mounted in the side walls 84 are bearings 86 for supporting the upper
flail member 70 in its proper vertical and lateral orientation. Preferably
35 bearings 86 are mounted in a structure capable of accommcdating the
vibrational moYement generated during operation and a suitable mounting
structure can irlclllde~ for exampl~, rubbar ~nounts. At ~h~ outP~d end ~d of
cie~arkin~ statlon 22 the b~ok ~rt~cal Y~2ll 8~ will t~rminate and pro~de a
lat~l olitf~ed op~n~ng 88. Simil~rly at Inf~d ~nd ~0 th~ ~r~nt w~ 7~t
t~rmln~t~s and provlda~ r~l op~nlng ~0 ~hrou~h whl~h the lo~ 3tem~ ~2
5 w~ll trnvaL Th~ openin~s ~8, ~0 rnu~t be slæacl BO th~r~ the ~llmen~ionQl rang~
oi Iog ~tem~ to be deb~rked wlll be ~ ommod~lte~l t,v1thout Jam up. ~t th~
outfe~d ~nd ~bov~ IataraI openln~ 8R an ou~ d roll (not shown~ or o~r
~ultRbI~ hotd~down nl~n~ could ~e provEcl~d E:~ ~ound n~e~ ry to pr~vlde
fldditlOnRI regtraEnt A~ tha debark~d log~ m~ ~sJt th~ d~b~ n~ tlon. I
10 th~ ~mbodsrn~nt d~pict~d ln Figure ~, th~ simpI~ ~lat pI~te meml~es~ 3
shown supportlng sterns 5~ ~o they leave ~tat~n ~,
T.he bottom enclo~ure :t'or b~tom ~lai1 ma~r1b~r 7~ i~ oornpri.~d,
simiIarIy to tho ~op en~lo~ure, o~ a subst~ntLally vertic~ ~ront wa~l m~,~nl'
~2 t?~ xt~nd~ Xly ~s~ h~ slZr~ b~lo~ ui~ 7.;0~
I5 A r~hr In~I1n~d I~t~rally ~xt~ndln~ wall ~ ~nd a. lat~"r~ll7,5~ ~.?Xtetlding ~tom
wa~ ~6 t~g~thRr wlth ~ tr~n~it10n w~I1 m~3mb~r ~a ~orril ~hF~ rest f3.~' ~.nC?
bottom e?n~lo~ure~ Tran~itioi~ w~1198 ~ in~ d upw~rdIy t~ rd ~'r~n~ w~
but ~ mina~e~ along ~ r~ hat ~ ~dJ~c~3n~ ~h~ lci~
011, ~ i37~ y ~ 3~t~ W~ 3i~ e~i'.ti'~?~ Q
a~ the Yo~llm~ w1th~ h~3 ~ oi~r~ lr3~ur~ i.rl~ fllt~
pr~Y~u~ly ~n~loned thi3 f;lat pllgt~ 3~ ~h~lt 3.~t~3r~ Iorl~lt~.~c~1rl~Ily In ~ e
~own am d tlon an væs a~ th~ Ollt d surfaca Ir~
tnoltn~ WQ~ to sub.~t~.n~i~lly evmpl~?ly ~n~lo~ ~he l('JW~31~ p
dabarklng statlorl~ Th~ bottom f1ail memt)~r 72 ~J g~ rly ~O I:Op ~ 1 7
25 m~unt~d in a p~ir o~ ~t~rtllly sp~d bearlngs 10~ supportecl withln ~Jtd~
w~ 102.
Tha ~nction ~I th~ slze redu~tlon .~tatiorl 100 l~ of course to
aoc~pt an incornlng now of limb~, br~nch~, .tollag~ and bark a~ ~eneratad
by fl~ll member~ 7U~ 72 and t~y the br~caga causecl by bottom rol1 4~ and
30 top roll ~ and to r~3duc~ it 1~ ~ize and then dir~ct it to a suitab1e
~tlownste~m lo¢a~ion. The flow of th~ m~t~riRl toward the ~Ize r~ductlon
~t~tlon 100 is gener~lly a3 d~picted In Figu~e 2 by ~low arrow~ 105 ~nd i8
~n~rally downwarclly ov~3r the rear in~31ine~ wa.U 941 th~ bottom w~ B, and
upwardly tt~ward th~ nip o~ ~ pE~ir of l~tera~:ly axt~nd}n~ ~hredd~r cylllldars
~5 10~, 108. Th~ shrecld~r cylind~ra I0~, 108 ~r~ w~ll known to tho~a 3killed in
th~ sl~e r~du¢tion ~rt and ar~ gen~rally comprised o~ ~ plur~lity o~ spaced
1~
shredder disks 109 having teeth elements 110 mounted on their periphery.
The cylinders 108, 108 rotate in the opposite direction toward each other at
the nip and draw material through the counter-rotating cylinders reducing it
in size as it passes through. The cylinders 106, 108 are mounted on suitable
5 bearings each indicated as 112 in Figure 1 with suitable drive means (such as
a hydraulic motor 113) connected thereto.
The debris dislodging means indicated at 114 under normal
circumstances forms a portion of the transition wall ~8 leading to the si~e
reduction station 100. Dislodging member 114 has a substantially flat upper
10 surface 116 and is mounted on a shaft 118 so that it may be rotated about a
suitable angle whereby it serves to dislodge any stagnant debris in the area.
Any suitable debris dislodging means may be utilized and in fact for some
operations it may not be needed at all. Positioned just below the outfeed of
the shredder cylinders 106, 108 is a debris slinging means generally indicated
15 at 12û. Slinging means 120 is mounted within enclosure 122 and is
comprised of a plurality of radially extending slinger arms each indicated as
124. Slinger arms 124 radiate outwardly from hub 126 which in turn is
connected to a rotatable shaft 128 which is driven by a suitable motor 130.
Motor 130 could, for example, be a suitably sized hydraulic motor. ~s the
20 debris, reduced in size, exits the reduction stat;on 100, the rotating slinger
arms 12~ will impart momentum to the debris causing it to travel radially
outwardly and then at an opening within enclosure 122 the debris will pass
outwardly therefrom9 for example7 through an upwardly extending chute 132
which is directed to a receiving receptacle (not shown). This is a very
25 convenient system for accumulating the debris produced by the debarking
sta tion and reducing it in size for convenient transport into an awaiting
receptacle such as a hog fuel bin.
DETAILS OF E~LAIL MEMBER
As depicted in Figure 2, the top and bottom flail members 70, 72
30 are offset longitudinally with each being enclosed within the enclosure for
debarking station 22. As depicted, each flail member is comprised in part of
a laterally extending rotatable drum, each indicated as 134. Mounted on the
surface OI a drum 134 is a plurality of attachments bars 136, each of which
serves to provide in part the attachment means for removably securing a
35 row of outwardly extending, laterally spaced chain segments each indicated
at 138. The chain segments 138 can be attached to the drums by any
ll
suitable means such as the attachment bars 136 as depicted. Attachment
bar 136 is comprised of a plurality of segments each indicated at 140 (see
Figures 4 and 5) which are removably mounted on drum 134 and which have
laterally extending pins 142 bridging a gap between adjacent segments 140.
The chain segments then are suspended from the pins 142. In order to
properly debark the traveling stems while in their side-by-side relationship,
the present flail structure is utilized and has been found to provide results
whereby substantially all of the bark is removed from the stems and the
chips produced from the debasked stems show a bark content of less than
10 1%.
As depicted, each drum 134 has six rows of chain segments
attached thereto and within each row there are a plurality of chain
segments 138, each terminating at substantially the same radial distance
when extended fully outwardly. In order to provide good coverage for the
15 chain segments as they impact the traveling stems for debarking purposes it
has been found that six rows of chain segments with approximate lateral
spacing on four-inch centers is adequate. In addition, it has been found that
it is preferable to laterally offset chain segments 138 in adjacent rows in
order to enhance bark removal. It has been found that extremely good
20 results are obtained when the chain segments in the upper flail member 70
are dimensioned so as to extend approximately two inches below the
horizontal feed plane and when the chain segments in the lower flail 72 are
dimensioned to extend upwardly above the feed plane when in the fully
extended position ~pproximately 1û inches. In view of the fact that the
25 normal size range for stems to be debarked will be from 4-12 inches, these
chain segment dimensions therefore give adequate coverage for debarking
and delimbing purposes. If the size range is increased, adjustments should
be made for chain length and one with ordinary skill in the art will easily be
able to design the structure for producing good results.
The chain segments 138 are essentially ordinary commercially
available sections of chain with certain modifications for the present
invention. On at least one of the flail members at least some of the chain
segments will have a lateral vibrational length that is less than the lateral
vibrational length of the other chain segments. By referring to Figure 4, it
35 will be seen that the chain segments indicated at 144 extend downwardly
from a plurality of circular links each indicated at 146. The plurality of
12
circular links 146 in turn are interconnected through a laterally spaced row
of interconnecting links each indicated at 148 to a plurality of inner circular
links 150 each of which depend from a respective pin 142 and are connected
thereto by links 152. In effect, the plurality of rings and links 146, 148, 150
and 152 form an interconnected chain mesh 154 from which will depend the
individual short chain segments 144. In the same flail member, the next
adjacent row of chain segments will be as depicted in Figure 5 with the
chain segment length in each case extending the length from its connecting
pin 142 to the last link. It has been found that to provide at least some of
10 the chain segments with operating lengths of approximately two thirds of
the dimension of full length chain segments results in impro~/ed bark
removal. When the individual chain segments are in operation, they will
continuously rotate and impact portions of the traveling stems. Each time a
chain segment impacts the solid surface of a stem it will react and have a
15 lateral oscillatory motion imparted thereto since it is a flexible member. Itin effect acts as a pendulum moving as a dynamic mass and incurs a lateral
transitory complex movement. Since it is a primary goal of the present
invention to provide complete debarking around the entire circumference of
each log stem as they pass through the debarking station, it was folmd
20 necessary to structure the motion of the chain segments in the dynamic
sense. It was discovered that by effectively shortening some of the chain
segments with the interconnecting chain mesh 154 that their side-to-side
vibratory motion could be changed with the shorter segments thereby
providing better impact coverage over the top and bottom surfaces of th
25 log segments. The lateral vibratory frequency is different than that of
longer chain segments and the shorter chain segments are designed to
impact the tops and bottoms of the log segments more frequently than they
wi~l impact along the sides. The longer chain segments provide the primary
impact coverage along the side portions of the traveling log stems. The
30 principles involved in vibratory dynamic motion are well known and can be
obtained in any textbook describing the principles of oscillatory motion and
the dynamics of moving masses. The chain mesh section 154 as depicted in
Figure 4 is a very convenient way to provide the shortening for the chain
segments, although other means could be employed such as by extending the
35 attachment bar radially outwardly. In the embodiment depicted and for
debarking trees in the diameter range of 4-12 inches, it is appropriate to
13
have the lengths of the chain segments be approximately 20 inches from the
pins to the tips of the last links. As will be described shortly, the working
length of the chain segments can be approximately 13 inchesO
It has been found that typical commercially available one half
5 inch chain link with the appropriate mass (such as 8620 steel) yields
excellent debarking results and that the flail drums operate most effectively
at approximately 4ao RPM as the stems pass through the debarking station
at a feed rate of approximately two feet per second.
It has also been found that with the above-noted flail speed and
10 feed speed not only are the tree stems completely debarked but the feed
speed through the debarking station is compatable with the operating
characteristics of a typical commercially available chipping machine so the
debarked stems can be fed directly into the mouth of a chipping machine.
The foLlowing table lists the parameters that affect debarking qualities
15 when practicing the present invention and also listed are the effective
ranges of parameters, in each case believed to be an effec~ive range.
~h ~
.t ~ ~3
1~ ,
Parameters that Affect Debarking Qualit
~Pre~erred'Value and Valu Range
Preferred Possible
Value Effective Value Range
Effecti~e flail diameter 52 in 52 + 14 in
Chain size (section dia.~ 0.5 in 0.60 + 0.20 in
Chain type Grade 80 Grade 40 or better
10 . Chain attachment position
.. Lateral offset 1.5 in 1.5 + 1.0 in
Chain density configuration
.. Rows per flail drum 6 rows 4-9 rows
.. Lateral spacing in row 4.2 in 4.2 + 1.0 in
15 . Flail drum diameter 12.5 in 12.5 -~ 6 in
Flaildrum RPM 400 RPM 300-5û0 RPM
Drum axis angle to feed line 90 83-97
Flail rotation direction (as viewed
from side with trees traveling
left to right)
.. Upper flail member CCW CCW
.. Lower ~lail member CW CW
Flail height (relative to horizontal
feed plane)
25 .. Upper (flail tip below bottom of
feed plane) 2 in 2.0 + 2.0 in
.. Lower (flail tip above bottom of
feed plane) 10 in 10.0 + 10 - 2 in
Tree feed speed through debarkation 105 ft/min 105 ~ 40 ft/min
station
It is believed that the ranges given will provide effective results
for users wishing to debark typical fiber quality stems to a standard of under
1.0% (bark content in chips) while minimizing damage to stem wood at the
35 same time. A high production rate is also maintainable when utilizing tlhese
parameters.
QUICK CONNECT LINK FOR CHAIN SEGMENTS
It is well known that the working ends of chain segments in chain
flail debarker/delimbers experience a significant amount of wear~ particu-
40 larly in the third link from the loose end. For example, in the publication
issued by the Canadian Forestry Engineering and Research Industrial
Commission (FERIC) in 197~ it is theorized that as the chain segments
impact the tra~eling stems, the bottom links bounce and rebound into the
third link causing considerable wear in the third link. Various solutions have
been attempted to overcome this problem, among them being to loop chain
5 segments, thereby eliminating loose ends. An innovative solution which has
been found to work quite well is the use of a quick connect link in each
chain segment 138 located approximately one third the distance between the
attachment bar and the last link of the section. Since the lower two thirds
of the length of each chain section is the primary working length, that is,
lû the length which will experience most of the impact against tree stems, it isthe portion receiving most of the wear. What is used is a quick connect link
in each chain section indicated at 156 in Figures 4 and 5. The purpose is to
allow the working ends of the chain sections to be quickly disconnected and
reversed, thereby evening out the wear and extending the life of each chain
15 segment. The quick connect link 156 is a specially modified U-shaped
segment of chain material. It is very clear from Figures 4 and 5 that the
quick connect link is a formed chain link that will reliably connect a chain
with small outside dimensions to a chain with large inside dimensions
(dimensions relative to each chain) so that the small chain will fit through
2~ the large chain. To connect the chains, connecting link 156 is slipped
through the end of the smaller chain until the bottom of the U of the
connecting link rests in the turn of the chain link. The smaller chain section
is then slipped through the link of the larger chain to which it will be
attached. The spread end of the connecting links do not fit through the
25 large link and the legs rest against the surface of the larger link, thereby
attaching the two chains. In the embodiment depicted the smaller chain
forming those links in the working end of the overall chain sections is
standard oval link chain while the larger chain link is a circular type link.
The length of each type of chain will be determined so that the overall
30 length of the assembly will be the required length for good performance.
The length of the smaller chain will be such that it could be reversed once
and all links will be worn before replacement. Even with reversing the
chain, only six links are usually particularly worn, therefore, if the chain
section was any longer, the user would be throwing away some good links at
35 the center of the section each time the chains are changed. ~3y using the
quick connect link and reversal technique with only six links in the working
16
section the replaced chain will be completely worn when replaced. Thus,
overall chain usage with the quick connect link should be about one half.
Another advantage is the standardization of replacement chain links. Any
variation in overall length of chain segments on the flail members can be
5 accomplished by changing the length of the larger chain mounted on the
drum.
OPERATION OF THE SYSTEM
Whether in mobile form or stationary form an operator will pick
up a collection of elongated tree stems and while the system can process
10 one stem at a time, it is designed to process a plurality of from two to six
depending on the diameter range in a side-by-side relationship. The
operator will pick up the collection and deposit them atop the infeed
conveyor where they will be spread out through gravity into a side-by-side
relationship. A conveyor will carry them into the debarking station where
15 the flail members will operate to impact the remaining limbs knocking them
from the stem and also the chain segments will impact the bark with the
impact energy knocking the bark from the stem. The rotating chain sections
serve to remove substantially all of the bark and remaining limbs. An
enclosure is designed so that the limbs and bark can be collected and
20 directed downwardly and then into the portion of the enclosure where a size
reduction means operates to reduce the size to transportable form. As the
debarked stems exit the debarking station, they can either be collected for
further processing or be transported directly into the opening of a close
coupled chipping machine in which they will be converted to usable chips.
25 Additional unique features in the flail members allow for easy maintenance
and longer life of those chain sections that are the working ends. In
addition, a novel feature in the flail members serves to provide complete
debarking around the entire circumference of each and every log stem as it
passes through the debarking station.
3~ While a detailed description has been given of an integrated
debarking system including several novel features, it will occur to those
skilled in the art that certain modifications and adjustments can be made to
either the apparatus or the process which will still be within the scope of
the inventive concept. All such changes and modifications are intended to
35 be included within the scope of the following claims.
