US2943656A - Pulpwood-debarking drum having angularly slotted wall and stationary shearing bars - Google Patents

Description

July 5, 1960 A. s. WAKEMAN PULPWOOD-DEBARKING DRUM HAVING ANGULARLY SLOTTED WALL AND STATIONARY SHEARING BARS 3 Sheets-Sheet. 1

Filed Aug. 24. 1956 INVENTOR. W

y 1960 A. G. WAKEMAN 2,943,656

PULPWOOD-DEBARKING DRUM HAVING ANGULARLY SLOTTED WALL AND STATIONARY SHEARING BARS Filed Aug. 24, 1956 3 Sheets-Sheet 2 & Z/NVEN TOR.

July 5, 1960 A. G; WAKEMAN 2,943,656

PULPWOOD-DEBARKING DRUM HAVING ANGULARLY SLO'IITED WALL AND STATIONARY SHEARING BARS 3 Sheets-Sheet 3 Filed Aug. 24, 1956 INVEN TOR.

nited States The present invention relates generally 'to the preparation of wood for pulping and, more particularly, relates to an apparatus and method for removingbark'from the slabs and edgings which result from sawmill operation so as to make these hitherto waste materials availablefor making various cellulosic products.

In various parts of the country there is a large amount of saw-mill waste which is useful only as fuel because it is in odd shapes and sizes. 7 Typical of this material are the so-called slabs which are cut from the sides or logs so as to provide a relatively flat-surfaced timber for use in the sawmill. Th'o'se slabs are generally arcuat'e in cross section, the curved side being covered with bark. Other waste material of this type are the so-called edgings which are cut from the edges of the rough boards in the initial sawmill operation. These edgings are also'covered with bark on one side.

Attempts have been made to employ slabs an'dedgings in paper-making operations but it has been very difficult to effect the removal of bark from the slabs so that clean, bark-free wood is available for the pulping operation. Economically, it is impossible to remove the bark from the slabs and edgings on a piece-by-piece basis because of the manual labor and the expense involved. On the other hand, attempts have been made to pass the slabs and edgings through ordinary barking equipment which is designed for the handling of pulpwood, i.e., lengths of wood 46 feet in lengths which are generally circular in cross section, but these attempts have met with failure. H

The usual barking equipment for ordinary pulpwood consists of a large elongated drum which may be from about to 12 feet in diameter and which may be from about 30 to 65 feet in length. These drums are made in the form of a cylinder which includes on the inner periphery thereof a series of circumferentially spaced, longitudinally extending bars having openings therebetween for permitting the bark to leave the drum. These openings are from about 2-4 inches wide and extend longitudinally of the drum. The pulpwood is fed into this drum which is rotated so that the pieces of wood rub upon one another and upon the bars so as to effect the removal of the bark, the bark passing out through the openings between the bars.

When slabs or edgings are put in such a barking drum, several difficulties manifest themselves. First, the edges of the individual pieces become wedged into the spaces between the longitudinal bars so as to jam the barkremoval openings. Second, the wedged pieces and the free pieces become so interentangled that there is a poor barking action and the load in the barking drum does not feed through the drum. And finally, in such an operation, the slabs and edgings are so broken up that they are of little use for paper-making operations since a great percentage of the wood is splintered and passes out of the drum with the bark toth'e'bark pile.

Accordingly, it the principal object of the invention to provide an apparatus and a method for elfecting the atent lQQ 2 removal of bark from sawmill waste such as slabs and edgings in an fefiicien't and economical manner. Other objects and "advantages of the invention will become known by reference to the appended drawings andthe following description of apparatus embodying the invention.

I Fig. l is a side elevation of a barking drum embodying various of the features of the invention;

Fig. 2 is an enlarged perspective view ofa section of the external surface of the drum shown in Fig.1;

Fig. 3 is a-verticah transverse sectional viewtaken on line 3-3 in Fig. l, a stationary partition at the end of the drum beingomitted;

Fig. 4 is an enlarged-scale, fragmentary, vertical, ,longitudinal, sectional view taken on line 44 in Fig. 3;

Fig. 5 is a vertical, transverse sectional view of a modified barking drum embodying features of the invention;

'Fig. 6 is a fragmentary, longitudinal sectional view taken on line 6'6 in Fig. 5; and v Fig. 7 is a fragmentary perspective view of a section of the modified barking drum shown in Figs. Sand 6.

In the drawings there are illustrated two embodiments of the invention which are adapted to be employed with slabs or edgings. The embodiment illustrated in Figs. 1 to 4, inclusive, includes generally a frame 1 1, a generally horizontally disposed barking drum 13, means 15 for supporting the barking drum for rotation about its longitudinal axis, means 17 for effecting the rotation of said drum, and shearing means 19 for severing and freeing any splinters or sticks which might become wedged in the barking drum 13; Of course, conveying means 21 are provided for feeding the slabs and edgings to the barking drum 13 as well as discharge conveying means 23 for carrying away the barked wood and a discharge conveyor means, 25 for .carrying away thebark which is removed from the wood. The embodiment illustrated in Figs. 5 to 7 inclusive, preferably includes the'features of the embodiment shown in Figs. l to 4 and, in-ad'dition, includes means 26 for preventing the slabs or edgings from becoming interentangled, thus insuring that each piece of wood is uniformly tumbled and subjected to barkingaction. H I v 7 The frame 11 in the illustrated structure is generally box-like and is fabricated from a number of structural members. The frame 1-1 includes a number of vertically extending support members 27 which are set in a suitable foundation 2% at their lower ends andwhose upper ends are, connected by a series of horizontally disposed longitudinal members 31 and transverse members 33 which provide a supporting platform for the support means 15 for the drum 13 and for the drum-rotating means 17. A second set of horizontally disposed transverse members 33a are provided between the vertical members 27 adjacent the lower ends thereof so as to reinforce thestructure and to provide a support means for the shearing means 19 which is adapted to act in co-operation with the barking drum 13. p

In the illustrated structure, the barking drum 13 comprises an elongated cylindrical shell 34 which may be fabricated from sheet steelor the like. In the interior of the shell there are provided a plurality of members 35 arranged around the periphery thereof which are aligned longitudinally of the shell and which are rigidly attached thereto.

The members 35 serve to reinforce the shell 34 and to provide projections for causing enough frictional force between the shell 34 and the slabs of wood being barked so that the slabs are carried with the shell as it rotates. The slabs finally fall back to the lower portion of the shell, the alternate lifting and falling action thus provided effecting the removal of the bark from the slabs. In the illustrated structure, the members 35 are fabricated from angle-iron structural members but various other shapes may be successfully employed as in the case of barking drums for pulpwood in standard sizes. In the illustrated structure, eight of the members 35 are employed but more or fewer may be employed without materially affecting the efficiency of the operation.

In order that the bark which is removed from the slabs may be removed from the interior of the shell 34 there are provided a number of narrow elongated slots 36 which are arranged generally longitudinally of the axis of the shell and preferably which are inclined relative to the axis of the shell. In the illustrated embodiment, the slots 36 are inclined relative to the axis of the shell 36 at an angle of about 15 (the angle on in Fig. 1), however, the exact angle'is not of particular importance.

The slots 36 desirably are wide enough to permit the stripped-off bark particles to pass therethrough but narrow enough so that sticks and large splinters which interfere with the free movement of material cannot become wedged therein. The preferred width has been found to be between about if; and inches, but wider and narrower widths may also be employed. The length of the slots 36 is not of great importance, however, it should be borne in mind that the length should be maintained within limits which will provide a strong shell structure.

As illustrated in the drawings, the drum 13 is supported for rotation in the frame 11 by the supporting means 15. The drum 13 may be supported in any suitable way as, for example, by mounting it on a set of trunnions. However, in the illustrated structure, the drum 13 is supported upon a series of sets of support chains and sprockets so as to more readily absorb stresses in the drum 13 due to the variations in load which occur under different working conditions.

Specifically, in the illustrated unit the drum is supported on the lower runs of four endless chains 37 which are longitudinally spaced along the dmm 13. Each of the chains 37 is supported on its upper run by means of a pair of sprockets 39 and 39a. Each of the sprockets 39 is rotatably supported on a longitudinally extending shaft 41 which is journaled for rotation in suitable bearings 43 (Fig. 3) which are supported on the upper transverse frame members 33. The sprockets 39 are adapted to rotate independently of the shaft 41 which, as will be hereinafter described, is employed as the drive shaft for the drum 13. Each of the sprockets 39w is supported in a slidable bearing 45 which is preferably spring biased as illustrated at 47 in Fig. 3 so as to maintain tension on its associated chain 37.

The chains 37 are each adapted to engage a sprocket ring 49 (Fig. 2) which is attached to and which extends around the circumference of the shell 34 in the plane of the sprockets 39 and 39a. Thus, the drum is cradled in the four chains 37 and is free to rotate. Longitudinal movement of the drum 13 as it is rotated is minimized by the chains 37, however, in order to effectively prevent both sidewise movement of the drum as well as longitudinal movement, a pair of guide rollers 51 are journaled on flanges 52 rigidly attached to the upright frame member 27 at each end of the unit. Each pair of rollers 51 rides in a flanged guide ring 53 (Fig. 2) which is attached to, and which extends circumferentially around, the outer surface of the shell so as to form a trackway for the guide rollers 51. The engagement of each pair of the rollers 51 in the channel provided by the associated guide ring 53 prevents sidewise movement of the drum 13 as it is rotated as well as longitudinal movement. However, this engagement does not prevent vertical movement of the drum incident to the stresses of operation.

The means for effecting rotation of the barking drum 13 in the illustrated structure includes a pair of drive chains 55, one of which is arranged at each end of the drum 13. The drive chains 55 each engage a sprocket ring 57 which extends around and which is attached to the outer surface of the drum 34. Each of the sprocket rings 57 on the drum 13 is operatively connected by the chain 55 to a sprocket 59 (Fig. 1) which is keyed to the shaft 41.

Rotation of the shaft 41 is effected by a driving connection with a suitable motor such as the electric motor 61 which is supported on the frame 11. The driving connection includes a drive belt 63 which interconnects a pulley 65 on the motor shaft with a pulley 67 on a countershaft 69. The countershaft 69 is journaled for rotation in suitable bearings 71 on the frame 11 and this countershaft is connected to the shaft 41 by a pair of speed-reducing gears 73 and 73a, keyed respectively to the shafts 69 and 41. The exact manner of rotating the drum is not important to the attainment of the objects of the invention and any suitable drive means which can accomplish the desired rotation of the drum is satisfactory.

As has been previously pointed out, a shearing means 19 is provided to co-operate with the drum 13 so as to sever any sticks or splinters which might become wedged in the slots 36 thereby causing the slabs to become jammed or entangled. The shearing means 19 includes a shearing bar 77 and a suitable mounting arrangement therefor. In the illustrated structure the mounting arrangement comprises a longitudinally extending mounting bar 75 (Figs. 3 and 4) which is rigidly connected to the transverse frame member 33a. The mounting bar 75 may conveniently comprise an angle-iron structural member, as illustrated.

As illustrated, the shearing bar 77 is mounted on the longitudinally extending mounting bar 75. The shearing bar 77 in the illustrated embodiment comprises a series of angle sections 77a (Fig. 4) which are suitably attached to the mounting bar 75 by a series of bolts 79 or the like. As shown, particularly in Fig. 4, the reason for providing the shearing bar 77 in the illustrated structure as a series of short bars rather than one long bar is the necessity of permitting the sprocket rings 49 and 57 and the chain 37 to pass therethrough. In the event that the drum 13 is mounted for rotation on trunnions, the shearing bar, of course, could be a single continuous length.

While various forms of shearing bars 77 may be employed, it has been found desirable to provide a shearing bar which is fabricated from an angle structural member which has the horizontal leg of the angle extending from the leading side of the vertical leg, considering the direction of relative movement of the shearing bar drum 13 as they approach one another. As shown in the drawings (Fig. 3) the drum rotates in the direction of the arrow 81 and the horizontal leg of the angle bar 77 extends to the right in that figure. As illustrated, the leading edge of the horizontal leg of the angle bar 77a may be sharpened to provide a cutting edge so as to facilitate cutting off any sticks or splinters which might protrude through and wedge in the slots 36. In the event that metal or the like becomes wedged in the slots 36, the drum is free to move upwardly against the weight of the drum so that the object may pass between the bar 77 21nd the drum 13 so as to minimize damage to the drum As has been pointed out, conveying means 21 are provided for conveying the slabs and edgings to the barking drum 13. The means 21 in the illustrated structure includes a belt conveyor 83 which discharges the slabs onto a chute 85 which is preferably arranged at an angle of between 30 and 60 to the horizontal. The chute 85 in addition to an inclined bottom surface 86 includes a pair of side walls 87 as shown in Figs. 1 and 3. The side walls illustrated are arranged to converge so that the appease slabs fall into the barking drum in'an aligned arrange 'ment.

13. The belt conveyor 91 discharges onto aconve'yor 93 which carries the bark to a disposal point. In order to insure that the bark falls onto the belt 91, a pair of sloping aprons 95 are provided, one on each sideo'f the belt 91 so as to direct the bark particles onto the belt. The aprons 95 are mounted on the frame 11 in any suitable fashion and are of the type ordinarily employed in commercial barking equipment.

Discharge of the barked slabs is effected by the conveyor means 23 which includes a chute 97 positioned at the discharge end of the barking drum 13. In order to cause the barked slabs to pass down the chute 7, a stationary partition 99 is provided to maintain a level of slabs in the drum while it is being rotated. Again, the spacing between the partition 99 and the discharge end of the barking drum 13 is such that the barked slabs will not fall therebetween. From the chute 9'7 the barked slabs pass onto a belt conveyor 101 which carries them to their point of ultimate use.

In operation, the drum 13 is rotated by the motor'61 through the driving connections which have been described. The slabs to be barked are fed onto the chute 85 whereupon they slide into the drum 13 in a substantially aligned relationship. As the drum is rotated it gradually fills with slabs to approximately /3 to /2 of its diameter and, as the slabs move towards the outlet end, the frictional forces occasioned by the slabs rubbing one upon the other due to the. rotation of the drum '13 which causes the slabs to tumble inside of the drum, effects the removal of the bark. The pulverized bark particles fall through the slots 36 onto the bark conveyor 25 which carries the bark to a disposal point. The slabs, after the bark has been removed, move out the outlet end down the chute 97 to the conveyor 101 which carries them to the point of utilization.

It has been found that various of the features of'the apparatus which have been described co-operate to produce an excellent barking action with'a minimum of damage to the slabs being handled.

One feature which'contributes to eificient operation is the arrangement of the slots 36 at an angle to the axis of the drum. It has been found that when the slots are arranged at an angle as illustrated the splinters and chunks do not become as readily wedged into the slots and the bark particles discharge more readily through the slots than in the case of slots which are parallel to the axis of the drum. The width of the slots also contributes to efficient operation and it has been found that slots from to /2 of an inch are desirable but somewhat wider or narrower slots may be employed.

Another feature of the barking drum which contributes to its efficient operation is the shearing. means 19 which on each revolution of the drum cuts off any sticks or splinters which may protrude through the slots 36. This insures that the slots remain open since it has been found that after the protruding end is cut ofi, movement of the load in the drum pulls the remaining portion ofthe wedged piece into the interior of the drum thereby clearing the slot.

In operating a barking drum of the type described on 1 slabs, it has been found that the length of the slabs being handled should be between about A to /6 of the diameter of the drum. Thus ithas been found desirable to employ a drum' having a diameter of from 8 to 12 feet for slabs which have been cut to a length of 2 feet. This promotes more eflicient barking action and results in faster barking.

The rate of rotation of the drum also may 'aid in obt'aininga well-barked product and it has been found that {the desirable speed of rotation is about 10 rpm. The s'peed-"of -rota-tion, however, depends upon the amount of or edgings from becoming interentangled and thus assures that each piece of slabs or edging is subjected to a uniform tumbling and barking action.

The means 26 illustrated in the drawings comprises the provision of a series of elongated baffie or strut members 103 which are interlaced in the interior of the barking drum so as to break apart any interentangled masses of Wood. The baffle members 103 may be structural-steel members such as angle iron or the like which can be bolted or otherwise fastened in place and which will act upon the slabs or edgings as they move through the drum. Preferably, however, the baffle members 103 are flexible so as to reduce fatigue failure in the members and to also provide for a slight swinging or yielding action as the members are moved through the mass of wood in the barking drum. Suitable flexible membersare link chains, cables or the like, or combinations of short chains or cable sections with short rigid sections to provide a memher which is relatively flexible. The most economical and satisfactory bafi'le members are chains and, accordingly, in the illustrated structure (Figs. 57) the members 103 comprise a plurality of chains. The members 103 maybe arranged in either a regular or haphazard pattern within the drum.

The bafile members 103 which are chains, may be arranged in a pattern such as shown in the drawings. In this pattern the members 103 are disposed so as to divide the drum into four segments, the members being stretched transversely across the drum 34 and longitudinally along the lengthof the drum so as to provide a combined crossed and zigzag pattern. Only one typical longitudinal section of the drum 34 is illustrated in Figs. 5-7 and this section shows only one of a series of coplanar chains 103a, each of which extends across the drum axis from a bracket 105, the latter being one of a longitudinal row of brackets attached to the inside wall of the drum, to a bracket 10511, which is one of an opposite row of brackets and which is longitudinally spaced toward the outfeed end of the drum, from the point of attachment of the bracket 105.

Another series of coplanar chains 103b, the common plane of which perpendicularly intersects the common plane of the chains 103a, are mounted inside the drum and are stretched across the drum axis, one of these chains 103!) being shown in Figs. 6 and 7 as extending between brackets 107 and 107a, which are-elements of two opposite rows of brackets, the point of attachment of the bracket 107a being longitudinally spaced, toward the infeed end of the drum, from the point of attachment of the bracket 107. Other chains 103a extend across the drum axis, but are stretched between the brackets 155 and those brackets 105a on the opposite wall which are spaced, from the brackets 105, toward the infe'ed end of the drum, whereby the chains 103a and 1030 form a zigzag pattern lengthwise of the drum. Still other chains 103d connect the brackets 107 with those brackets 107a on the opposite'wall which are longitudinally-spaced, to-

ward the outfeed end of the drum, from the brackets 107, so as to form a second zigzag pattern of chains lengthwise of the drum. Thus, each zigzag pattern comprises a series of coplanar chains, and the two patterns define perpendicular planes that intersect each other along the drum axis. The arrangement which has been described involves a regular pattern. However, the advantages of the invention are equally well secured with a haphazard pattern of chains or baffling means within the interior of the drum.

The bafile members 103 may be located throughout the length of the drum 34 or they may be located only in the regions where the wood becomes interentangled to such an extent that it does not effectively rub off the bark surfaces of the pieces being barked. In operation, it has been found that the provision of the members 103 greatly enhances the barking eificiency of a barking drum and at the same time does not unduly increase splintering of the wood being barked.

In the foregoing there has been described an improved apparatus for barking slabs and edgings, which have hitherto been waste material, so as to make them available for use as pulpwood. As has been pointed out, the various features of the apparatus co-operate to provide an efficient means for accomplishing the barking of this class of materials which has not been possible with the prior art machines.

Various features of the invention are set forth in the appended claims.

I claim:

1. In an apparatus of the class described adapted for use in barking slabs of the wood, an elongated cylindrical shell having an inlet at one end for bark-bearing wood and an outlet at the other end thereof for barked wood, said shell having a plurality of circumferentially spaced, narrow, elongated, generally longitudinally extending openings in the sunface of said cylinder through which bark may pass outwardly from the interior of said cylinder, said openings having a width of from about to /2 inch, and means for rotating said shell about its longitudinal axis.

2. In an apparatus of the class described adapted for use in barking slabs of wood, an elongated cylindrical shell having an inlet at one end for bark-bearing wood and an outlet at the other end thereof for barked wood, said shell having a plurality of circumferentially spaced, narrow, elongated openings in the surface of said cylinder through which bark may pass outwardly from the interior of said cylinder, said openings being arranged at an angle of about 15 relative to the longitudinal axis of said shell, and means for rotating said shell about its longitudinal axis.

3. In an apparatus of the class described adapted for use in barking slabs of wood, an elongated cylindrical shell having an inlet at one end for bark-bearing wood and an outlet at the other end thereof for barked wood, said shell having a plurality of circumferentially spaced, elongated openings in the surface of said cylinder through which bark may pass outwardly from the interior of said cylinder, said openings having a width of from about to /2 inch, said openings being arranged at an angle to the longitudinal axis of said shell, and means for rotating said shell about its longitudinal axis.

4. In an apparatus of the class described adapted for use in barking slabs of wood, an elongated cylindrical shell having an inlet at one end for bark-bearing wood and an outlet at the other end thereof for barked wood, said shell having a plurality of circumferentially spaced, narrow, elongated, generally longitudinally extending openings in the surface of said cylinder through which bark may pass outwardly from the interior of said cylinder, means for rotating said shell about its longitudinal axis, and stationary means extending along the outer surface of said cylinder in the region of said openings,

. said stationary means overlying the entire longitudinal extent of the path traveled by each of said openings and extending in close proximity to said openings for shearing-ofi any material which extends through said openings.

5. In an apparatus of the class described adapted for use in barking slabs of wood, an elongated cylindrical shell having an inlet at one end for bark-bearing wood and an outlet at the other end thereof for barked wood, said shell having a plurality of circumferentially spaced, narrow, elongated, generally longitudinally extending openings in the surface of said cylinder through which bark may pass outwardly from the interior of said cylinder, means for rotating said shell about its longitudinal axis, and a bar disposed in close proximity to the outer surface of said shell and generally parallel to the longitudinal axis thereof, said bar extending across the path traveled by each of said openings, and a stationary support for said bar, said bar being effective to shear-off any material which extends through said openings incident to the rotation of said shell.

6. In an apparatus of the class described adapted for use in barking slabs of wood, an elongated cylindrical shell having an inlet at one end for bark-bearing wood and an outlet at the other end thereof for barked wood, said shell having a diameter of between about 4 and 6 times the length of slabs of wood being barked and being provided with a series of circumferentially spaced, narrow, elongated openings therein through which bark may pass outwardly from the interior of said cylinder, said openings being arranged at an angle relative to the longitudinal axis of said shell, the interior of said shell being provided with a plurality of longitudinally extending members which are attached thereto, said members being adapted to engage slabs of wood being debarked and to aid in imparting a tumbling action thereto, means for rotating said shell about its longitudinal axis, and stationary means extending along the outer surface of said cylinder in the region of said openings and in close proximity thereto for shearing off any material which extends through said openings.

7. In an apparatus of the class described adapted for use in barking slabs of wood, an elongated cylindrical shell having an inlet at one end for bark-bearing wood and an outlet at the other end thereof for barked wood, said shell having a diameter of between about 4 and 6 times the length of slabs being barked and being provided with a series of circumferentially spaced, narrow, elongated openings therein through which bark may pass outwardly from the interior of said cylinder, said openings being arranged at an angle relative to the longitudinal axis of said shell and having a width of from about /3 to /2 inch, the interior of said shell being provided with a plurality of longitudinally extending members which are attached thereto, said members being adapted to engage slabs of wood being barked and to aid in imparting a tumbling action thereto, means for rotating said shell about its longitudinal axis, and stationary means extending along the outer surface of said cylinder in the region of said openings and in close proximity thereto for shearing off any material which extends through said openings.

8. In an apparatus of the class described adapted for use in barking slabs of wood, an elongated cylindrical shell having an inlet at one end for bark-bearing wood and an outlet at the other end thereof for barked wood, said shell having a plurality of circumferentially spaced openings in the surface thereof through which bark may pass outwardly from the interior of said shell, the interior of said shell being interlaced with a plurality of chains which are stretched across the interior of said shell and which are adapted to break apart interentangled pieces of wood being barked, said chains being positioned in such manner that they are directed transversely as well as longitudinally of the interior of said shell, and means for rotating said shell about its longitudinal axis.

9. In an apparatus of the class described adapted for use in barking slabs of wood, an elongated cylindrical shell having an inlet at one end for bark-bearing wood and an outlet at the other end thereof for barked wood, said shell having a plurality of circumferentially spaced openings in the surface thereof through which bark may pass outwardly from the interior of said shell, the interior of said shell being interlaced with a plurality of chains which are spaced longitudinally of the drum and stretched across the interior of said shell in crossed and zigzag arrangement and which are adapted to break apart interentangled pieces of wood being barked, and means for rotating said shell about its longitudinal axis.

10. In an apparatus of the class described adapted for use in barking slabs of wood, an elongated cylindrical shell having an inlet at one end for bark bearing wood and an outlet at the other end thereof for barked wood, said shell having a plurality of circumterentially spaced, elongated openings in the surface of said cylinder through which bark may pass outwardly from the interior of said cylinder, said openings having a width of from about to inch, said openings being arranged at an angle to the longitudinal axis of said shell, the interior of said shell being interlaced with a plurality of flexible, elongated biafile members which are attached at each end to the interior of said shell and which are adapted to break apart inter-entangled pieces of wood being barked, and means for rotating said shell about its longitudinal axis.

11. In an apparatus or the class described adapted for use in barking slabs of Wood, an elongated cylindrical shell having an inlet at one end for bark-bearing wood and an outlet at the other end thereof for barked wood, said shell having a plurality of circumferentially spaced, narrow, elongated, generally longitudinally extending openings in the surface of said cylinder through which mark may pass outwardly from the interior of said cylinder, the interior of said shell being interlaced with a plurality of flexible, elongated bafile members which are attached at each end to the shell and are adapted to break apart interentangled pieces of the 'wood being barked, means for rotating said shell about its longitudinal axis, and a stationary bar disposed in close proximity to the outer surtace of said shell, said bar overlying the entire longitudinal extent of the path traveled by each of said openings, and a stationary support for said bar, said bar being effective to shear-off any material which extends through said openings incident to the rotation out said shell.

12. In an apparatus of the class described adapted iior use in barking slabs of wood, an elongated cylindrical shell having an inlet at one end tor bark-bearing wood and an outlet at the other end thereof for barked wood, said shell having a plurality of circumterentially spaced, narrow, elongated, generally longitudinally extending openings in the surface of said cylinder through which bark may pass outwardly from the interior of said cylinder, the interior of said shell being interlaced with a plurality of chains which are attached at each end to the interior of said shell and which are adapted to break apart interenltangled pieces of the wood being barked, means for rotating said shell about its longitudinal axis, and a stationary bar disposed in close proximity to the outer surface of said shell, said bar overlying the entire longitudinal extent of the path traveled by each of said openings, and a stationary support for said bar, said bar being effective to shear-off any material which extends through said openings incident to the rotation of said shell.

13. In an apparatus of the class described adapted for use in barking slabs of wood, an elongated cylindrical shell having an inlet at one end for bark-bearing wood and an outlet at the other end thereof for barked wood, said shell having a diameter of between about 4 and 6 times the length of slabs of wood being barked and being provided with a series of ciroumterentially spaced, narrow, elongated openings therein through which bark may pass outwardly from the interior of said cylinder, said openings being arranged at an angle relative to the longitudinal axis of said shell, the interior of said shell being provided with a plurality of longitudinally extending members which are attached thereto, said members being adapted to engage slabs of wood being debarked and to aid in imparting a tumbling action thereto, means for rotating said shell about its longitudinal axis, the interior of said shell being interlaced with a plurality of chains which are attached at each end to the interior of said shell and which are adapted to break apart interentangled pieces of wood being barked, and stationary means overlying the entire longitudinal extent of the path traveled by each of said openings and in close proximity to the outer surface of said cylinder for shearing oif any material which extends through said openings.

References Cited in the file of this patent UNITED STATES PATENTS 1,247,526 Guettler n Nov. 20, 1917 1,324,193 Guettler Dec. 9, 1919 1,974,493 Hellner l l Sept. 25, 1934 2,599,090 Clark et a1. June 3, 1952 2,712,330 Thompson July 5, 1955 FOREIGN PATENTS 52,015 Norway Jan. 16, 1933 85,739 Norway June 20, 1955

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