CA1249205A - Flail member for debarking trees - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

This invention covers a flail member of the type useful in a debarking system for removing bark from logs as the logs travel relative to the flail member through a debarking station. The flail member has a plurality of laterally spaced chain segments mounted on a rotatable member with the segments arranged in a plurality of rows, and at least some of the chain segments have different lengths for example approximately 2/3 that of the other chain segments in order to provide a different lateral vibratory frequency upon impact with the logs.

Description

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.

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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.

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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 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 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.

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.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 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.

Claims (5)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A flail member of the type useful in a debarking system for removing bark from logs as the logs travel relative to the flail member through a debarking station, having the improvement comprising:
a plurality of laterally spaced chain segments mounted on a rotatable member with the segments being arranged in a plurality of rows, and at least some of the chain segments having different lengths in order to provide a different lateral vibratory frequency upon impact with the logs.

2. The improvement as in claim 1 in which at least some of the chain segments have an effective vibratory length of approximately 2/3 that of the other chain segment.

3. The improvement as in claim 1 in which the chain segments of shorter lengths are attached radially outwardly on the rotatable member compared to the longer chain segments.

4. The improvement as in claim 1 in which the attachment means for the shorter chain segments includes an interconnected chain mesh from which the shorter chain segments depend.

5. The improvement as in claim 1 in which substantially all of the chain segments have their tips, when extending radially outwardly, in a right cylindrical plane.