US2891588A - Slitter-disk bark-stripping apparatus - Google Patents

Description

June 23, 1959 w. M. ALLEN 2,891,588

'SLITTER-DISK- BARK-STRIPPING APPARATUS Fi led Feb. 26. 1958 i1 Mimi m;

INVENTOR- WILLIAM M. ALL EN United States Patent SLITTER-DISK BARK-STRIPPING APPARATUS William M. Allen, Columbus, Ohio, assignor to Battelle Memorial Institute, Columbus, Ohio, a corporation of Ohio Application February 26, 1958, Serial No. 717,698

13 Claims. (Cl. 144--208) This invention relates to apparatus for removing bark from logs and slabs. More particularly, it relates to apparatus for removing the bark from log and slab portions of logs by the method of stripping the bark from the log in continuously longitudinal progression.

Two of the most well-known manners of removing bark from logs are: (1) chipping the bark away from the surface of the log or slab by means of a plurality of knives arranged to cut and extract the bark in small fragments or chips; and (2) the use of knives and wedge plates arranged to pass longitudinally with respect to the axis of the slab or log and to cut from and wedge beneath the bark.

Usually, in the method of (l), rapidly rotating knives are provided and the bark is removed in small segments by the chiseling effect of the knives. On the other hand, in the method of (2), the bark is longitudinally separated into longitudinal segments after which a tearing or wedging force is created between the bark and the wood of the tree, at the position of the cambium layer. The wedging force overcomes the tension in this layer and the bark peels away from the wood at the natural line of separation between the two.

This invention relates to apparatus for accomplishing this latter method moresuccessfully and with greater efficiency than previously known.

Briefly, in this invention rotatable slitter disks of a particular and critical configuration are disclosed which arev adapted to roll upon the surface of the log while cutting segments of bark and peeling these segments of the bark from the wood by wedging the bark laterally. These disks are provided with a rolling contact surface having a beveled portion tapering from one side toward the other to meet a cutting portion projecting radially from the beveled surface. These disks are held at a particular specified attitude or position with respect to the log and bark. The disks of this invention are in a canted and toe-in position with respect to a longitudinally disposed radial plane of the log.

Difficulty has been experienced in the past in peeling the bark from logs because of the varying tightness with which it sticks to the log during different seasons of the year. Timber which is cut in the spring and summer may be easily debarked by the peeling method because of the relative ease with which the bark breaks away from the tree at the cambium layer. On the other hand, logs which are cut in the fall and winter of the year have proven to be very difiicult to debark by peeling methods. In addition to the tenacity between the bark and the wood in the cambium area at this time of the year, in

many instances the bark is filled with moisture that is frozen, holding the bark in place. Insofar as is known, the conventional bark-peeling apparatus, such as wedges and knife-edge cutters, have not proven to be successful in more than a'lim'ited number of applications where conditions are decidedly favorable. Debarking in the Winter time by this method has been very unsuccessful.

Another difliculty is that different species of woods debark differently.

It is therefore an object of this invention to provide apparatus which may be successfully operated on a variety of difierent species of wood including white pine, yellow pine, and fir during both the winter season and the summer season. It is a further purpose to provide apparatus for peeling the bark from logs and slabs that is compact and sufiiciently portable to be taken apart into smaller components and easily transported. It is an object of the inventionv to provide bark-removing apparatus which will cleanly remove the bark from the log leaving a very minimum bark contamination on the log.

To these and other ends, this invention comprises apparatus, the preferred form of which is disclosed in the following description and attached drawings. Although the apparatus and structure described and shown in detail refer with particularity to a machine for stripping the bark from portions of log or slabs, it is apparent that this invention should not be limited thereto. Many of the significant details of this'invention applied with equal qualification may be applicable to shavers in other branches of technical endeavor. The invention may be used for other purposes where its features are advantageous,

In the drawings:

Fig. l is a plan view of the general layout'of the apparatus of this invention;

Fig. 2 is an elevation of the apparatus shown in Fig. 1;

Fig. 3 is a fragmentary enlarged-scale, vertical section taken on the line 3-3 of Fig. l, and shows a schematic diagram of the slitter disk of this invention in operative position; I I

Fig. 4 is a plan view of the slitter disk at the same position; and

Fig. 5 is an enlarged elevation of a portion of the rolling contact surface of the slitter disk of this invention. 1

The apparatus of this invention to be described in detail is specifically adapted to debark slabs of logs. However, it should be' understood that the apparatus is equally applicable to debarking full log segments, since slabs is the name conventionally used for portions 'of a log obtained by cutting ona chord of the circular cross section ofthe log. t

Referring to Fig. l, .the apparatus disclosed comprises two cooperative portions. A debarker portion 10 is at the entrance end of the apparatus. A chipper portion 11 is positioned to receive debarked slabs and reduce them to chips.

The debarker unit 10 comprises a centrally positioned, substantially horizontal conveyor 12 supported in a frame 13 and driven by a gear motor 14 at one end. The conveyor 12 is positioned to receive at one end 17 a slab 15 with bark 16 in place as shown. The slabs 15 are placed on the conveyor 12 with their longitudinal axes parallel to the longitudinal axis of the conveyor 12. In order to provide a grip on the slab 15, the surface of conveyor 12 has means to engage and press into the surface of the slab 15. This means may be a plurality of protruding pins 25. Slabs 15 are first conveyed beneath a pressure roll 18 which holds the slabs firmly in contact with the conveyor belt 12. Secondly, the conveyor belt 12 carries the slabs 15 beneath a plurality of slitter disks 19, 20, 21, 22, and 23. As most clearly seen in Figs. 1 and 2, the slitterdisks 19-23 are positioned in progressively spaced'relation longitudinally along the path of travel of the slab 15. In a manner that is described in detail later herein, the disks 19-23 roll on the slab 15 as it progresses beneath them, and the bark 16 *is loosened and peeled from the wood.

After passing beneath the slitter disks 19-23, the slab is carried beneath a pair of brushes 24 which are supported from an upper portion 57 of the frame 13 (Fig. 2). The brushes 24 serve to push the bark 16 that has been freed by the slitter disks 19-23 laterally to the edges of the slab 15 where it falls on the surface of a chute 26 at either side of the conveyor 12.

Leaving the brushes 24, slab 15 passes beneath a second pressure roll 27 which assures that there is a firm contact between the bottom of the slab 15 and conveyor belt 12 so that the slab 15 is firmly held and progresses with the belt 12. The continued progression of slab 15 carries it beneath a driven wheel 30 as it leaves the end of conveyor 12. The driven wheel 31 may be conveniently operated through a chain drive 36 by the gear motor 14. The wheel 30 forces the end of the slab into the path of a plurality of rapidly rotating chipping knives 31 which are supported on a fiywheel 32 that is driven by an electric motor 33. The speed and force of the chipping knives causes the end of the slab to be flaked into a large quantity of chips which is carried by momen tum out through an aperture 34 in an enclosure 35 which surrounds the chipping wheel 32. The aperture 34 may be connected in communication with a storage bin or place where the chips are used.

This invention is primarily concerned with the barkremoval portion of the apparatus 10. It has been found that the bark may be removed from white pine, yellow pine, and fir during both the winter and summer season by the apparatus of this invention including slitter disks 19-23 having a rolling contact surface of the following configuration.

The slitter disks 19-23 are constructed with a rim portion 41) having a beveled surface 41 tapered to meet a cutter side 44 in an acute angle a. An annular cutting portion 43 protrudes radially outward beyond the beveled surface 41. Tests have shown that the configuration of the rim is more than a matter of choice. It has been found that the portion 41 should be beveled at a very large acute angle and that an angle of about 70 degrees for or gives optimum results. The provision of a large acute angle makes the beveled surface 41 act as a flange to some degree, and prevents the cutting portion 43 from penetrating too deeply. It has also been found that, in a typical slitter disk having a thickness of about /1 inch from one side 42 to the other side 44, the cutting portion 43 should protrude beyond the surface of the beveled surface 41 about A inch. The optimum protrusion is therefore about of the width of the rim 40.

In the operation of the slitter disk, a slab 15 is carried in a linear path past the position of the disk. Slab 15 is held so that the line of travel of the cutting portion 13 enters the bark 16 and cuts a groove therein. Simultaneously, the beveled surface 41 exerts a lateral force on the bark while the wood of the slab 15 is prevented from lateral movement. This provides a shearing force in the cambium layer where the bark 16 is attached to the wood of the slab 15 causing a lateral rupture. Bark 16 is displaced laterally and thereby removed from its positions on the wood.

The apparatus for holding the slitter disks 19-23 cornprises means for resiliently forcing these members into contact with the bark 16 and means for holding the shafts upon which the disks rotate in position to move radially with respect to the center of curvature of the surface of the slab without movement either tangentially or longitudinally.

Referring to Fig. 2, the means for resiliently holding and forcing the slitter disks 19-23 toward the slab may comprise air cylinders operating piston rods 51 which support the slitter disks 19-23 in yokes 52.

The means for supporting slitter disks 19-23 in the opposite direction may comprise a plurality of swingable arms 53 rotatively supporting the shafts of the slitter disks 19-23 at one end 54. The arms 53 are pivotally supported at the opposite end 55 by a plate 56 which is connected to the upper portion 57 of the frame 13. The cylinders 50 may be connected to a source of compressed air at adjustable pressure. As a slab 15 makes initial contact with the first two slitter disks 19 and 2d, the end of the slab and the bark lifts them up. The lifting action on the disks 19 and 211 is resisted by the resilient compressible force exerted by the air pressure in the piston 50. The slitter disks 1.9 and 211 are guided in their upward movement by the swinging action of arms 53. The amount of pressure exerted by the rolling contact surface 411 of the slitter disks 19-23 may be adjustably controlled by the amount of air pressure in the pistons 51).

In the apparatus of the example, slitter disks 20, 22, and 23 are positioned with the cutting portion 43 at one side. Slitter disks 19 and 21 are oppositely positioned. The disks 2%, 22, and 23 move the bark laterally to one side, while on the other hand, disks 19 and 21 move the bark in the opposite direction.

in addition to the significant improvement in the results obtained in the use of this debarking apparatus by means of the configuration of the rim 40 that has been disclosed, it has been found that results can be further improved by supporting slitter disks 19-23 in a particular position with respect to the surface of the slabs 15 and with respect to the line of travel or path of movement of these slabs 15.

Referring to Figs. 3 and 4, slab 15 is indicated as having a substantially curved outer surface covered by bark 16 at one side of the slitter disk 23. It will be understood, of course, that the designation of the slitter disk 23 in Figs. 3 and 4 is by way of example only, as all of the slitter disks 19-23 are of similar construction and operated in the same manner.

By way of illustration, slab 15 in Fig. 3 is considered to be passing away from the viewer and the axis 54 of slitter disk 23 may be considered to be stationary. In a like manner, in Fig. 4 the axis 54 of slitter disc 23 may be considered stationary, and slab 15 is moving toward the two arrows with respect thereto. It has been found that in order to obtain optimum debarking action as slitter disk 23 moves along the surface of the wood, making contact at a momentary point 60 on a longitudinally disposed radial plane represented by the line 61, the disk 23 should be at a canted position with respect to the plane 61 at an angle 6 (Fig. 3). An angle 6 of about 15 has been found to be effective. It has also been found that the disk 23 should be toed in at an angle (Fig. 4) with respect to the plane 61. An angle of about 15 has been found to be effective. During the passage of the slab 15 beneath the disk 23, the frictional resistance of the rim 40 on the bark 16 and wood of the slab 15 causes the disk 23 to roll without the provision of any external power applied thereto. The rolling action with the canted and toe-in position of the disk 23, together with the beveled surface 41 and the cutting portion 43 provide a unified cutting, twisting, wedging force on the bark. This has been found to effectively strip the bark from the wood cleanly under the most adverse conditions. For example, freshly cut slabs from trees felled during the month of January were debarked by the apparatus of this invention cleanly to the surface of the wood at the cambium layer at a rate of progress along the surface of the wood of llO feet per minute. This operation Was carried out repeatedly with similar results in which the bark remaining before the debarked slabs had been re duced to chips was only 0.2 percent. Tests with debarkers of other configurations, such as sharply pointed and angled edges, showed 8.7 percent remaining bark.

It will be understood, of course, that, while the forms of the invention herein shown and described constitute the preferred embodiments of the invention, it is not intended herein to illustrate all of the possible equivalent forms or ramifications of the invention. It will also be understood that the words used are words of description, rather than of limitation, and that various changes, such as changes in shape, relative size, and arrangement of parts may be substituted without departing from the function or scope of the invention herein disclosed.

What is claimed is: V

1. Apparatus for removing bark from a log comprising: a first support and a second support movable with respect thereto; said second support constructed to receive and firmly hold a workpiece portion of a log with the bark in place on the log as grown; a disk carried by the first support in a position of rolling contact on said log portion as said second support moves with respect to said first support; a rolling contact surface on said disk including a beveled portion tapering from one side toward the other and meeting a cutting portion; said disk being held in a canted position with respect to a tangent plane at the circumference of the log and said disk being toed in with respect to the line of the travel of said log portion.

2. Apparatus for removing bark from a log comprising: a first support and a second support movable linearly with respect thereto; said second support constructed to receive and firmly hold a workpiece portion of a log having the bark in place on the log as grown, in position with the longitudinal axis of the log substantially parallel to the line of movement between said first and second supports; a disk carried by said first support in a position of rolling contact on said log portion as said second support moves with respect to said first support; a rolling contact surface on said disk including a beveled portion tapering from one side toward the other and meeting a cutting portion; said disk being held in a canted position with respect to a tangent plane at the circumference of the log and said disk being toed in with respect to the line of the travel of said log portion.

3. Apparatus for removing bark from a log comprising: a first support and a second support movable linearly with respect thereto; said second support constructed to receive and firmly hold a workpiece portion of a log having the bark in position on the log as grown, in position with the longitudinal axis of the log substantially parallel to the line of movement between said first and second supports; a disk carried by said first support in a position of rolling contact on said log and rolling by frictional resistance on the bark of said log as the second support moves with respect to the first support; a rolling contact surface on said disk including a beveled portion tapering from one side toward the other and meeting a cutting portion radially projected beyond the plane of the bevel; said disk being held in said first support in canted position with respect to a tangent plane at the circumference of the log and said disk being toed in with respect to the line of the travel of said log.

4. Apparatus for removing bark from a log comprising: a first support and a second support moveable linearly with respect thereto; said second support constructed to receive and firmly hold a workpiece portion of a log with the bark in place on the log as grown, positioned with the longitudinal axis of the log substantially parallel to the line of movement between said first and second supports; a disk carried by said first support in a position of rolling contact with said log, rolling without external rotative power supply on the log as the second support moves with respect to the first support; a rolling contact surface on said disk including a beveled portion tapering from one side toward the other and meeting a cutting portion projecting beyond the plane of the bevel; said disk being held in said first support in canted position with respect to a tangent plane at the circumference of the log and said disk being toed in with respect to the line of the travel of said log.

5. Apparatus for removing bark from a log comprising: a first support and a second support movable linearly with respect thereto; said second support member constructed to receive and firmly hold a workpiece portion of a log having the bark in place on the log as grown, in position with the longitudinal axis of the log substantially parallel to the line of movement between said first and second supports; a diskcarried by said first support in a position of rollingcontact on said log portion as said second support moves with respect to said first support; a rolling contact surfaceon said disk including a beveled portion tapering from one side toward the other and meeting a cutting portion; the axis of rotation of said diskgbeing held in said first support at a position to tilt and toe in the radial'plane of said disk with respect to a longitudinal plane radially through said workpiece at the point of disk contact therewith.

6. Apparatus for removing bark from a log comprising: a first support and a second support movable linearly with respect thereto; said second support constructed to receive and rigidly hold a workpiece portion of a log having the bark in place on the log as grown, in position with the longitudinal axis of the log substantially parallel to the line of movement between said first and second supports; a disk carried by said first support in a position of rolling contact on said log portion as said second support moves with respect to said first support; a rolling contact surface on said disk including a beveled portion tapering at a large acute angle from one side toward the other and meeting a cutting portion; the axis of rotation of said disk being held in said first support at a position to tilt and toe in the radial plane of said disk with respect to a longitudinal plane radially through said workpiece at the point of disk contact therewith.

7. Apparatus for removing bark from a log according to claim 6 wherein said rolling contact surface on said disk is beveled at a large acute angle on one side only.

8. Apparatus for removing bark from a log comprising: a first support and a second support movable linearly with respect thereto; said second support constructed to receive and firmly hold a workpiece portion of a log having the bark in position on the log as grown, in position with the longitudinal axis of the log substantially parallel to the line of movement between said first and second supports; a disk carried by said first support in a position of rolling contact on said log and rolling by frictional resistance on the bark of said log as the second support moves with respect to the first support; a rolling contact surface on said disk including a beveled portion tapering from one side toward the other and meeting a cutting portion; the axis of rotation of said disk being held in said lrrst support at a position to tilt and toe in the radial plane of said disk with respect to a longitudinal plane radially through said workpiece at the point of disk contact therewith.

9. Apparatus for removing bark from a log according to claim 8 wherein said beveled portion tapers from one side toward the other at a large acute angle.

10. Apparatus for removing bark from a log according to claim 9 wherein said tapering beveled portion tapers trom one side only at a large acute angle.

11. Apparatus for removing bark from a log comprising: a first support and a second support movable linearly with respect thereto; said second support constructed to receive and firmly hold a workpiece portion of a log having the bark in position on the log as grown, in position with the longitudinal axis of the log substantially parallel to the line of movement between said first and second supports; a disk carried by said first support in a position of rolling contact on said log and rolling by frictional resistance on the bark of said log as the second support moves with respect to the first support; a rolling contact surface on said disk tapering from one side toward the other at an acute angle of about 70 degrees with respect to the radial plane of the disk and meeting a cutting portion extending beyond the face of the beveled portion about the width of the disk; the axis of rotation of said disk being held in said first support at a position to tilt and toe in the radial plane of said disk with respect to a longitudinal plane radially through said workpiece at the point of disk contact therewith.

12. In a debarking apparatus a slitter disk rotatively carried imposition for rolling contact on a portion of a log having bark, by frictional'resistance on the surface of said bark, said disk having a rolling contact surface including a beveled portion tapering from one side toward the other and meeting a cutting portion protruding radially beyond the beveled portion of said disk.

13. In a debarking apparatus, the improvement C0111- prising a slitter disk rotatively carried by said apparatus in position for rolling contact by frictional resistance on the bark of a workpiece to be debarked, said disk having a rolling Contact surface including a beveled portion tapering from only one side toward the other at an angle of about 70 degrees with the radial plane of the disk and meeting a cutting portion extending beyond the bev- 8 eled surface of the disk for a distance of about of the width of the disk.

References Cited in the file of this patent UNITED STATES PATENTS Re. 23,765 Pauley et a1. Jan. 5, 1954 1,673,265 Pangborn June 12, 1928 1,887,908 Tidblad Nov. 15, 1932 2,452,631 Cameron Nov. 2, 1948 10 2,684,098 Graham et al. July 20, 1954 FOREIGN PATENTS 154,716 Sweden June 5, 1956

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