US3347291A

US3347291A - Apparatus and knife for the production of wood chips from logs

Info

Publication number: US3347291A
Application number: US425493A
Authority: US
Inventors: Wexell Harry Wilhelm
Original assignee: Brundell and Jonsson AB
Current assignee: Brundell and Jonsson AB
Priority date: 1965-01-14
Filing date: 1965-01-14
Publication date: 1967-10-17
Anticipated expiration: 1984-10-17
Also published as: DE1528304A1

Description

H. W. WEXELL APPARATUS AND KNIFE FOR THE PRODUCTION Oct. 17, 1967 3,347,291

OF WOOD'CHIPS FROM LOGS Flled Jan 14 1965 4 Sheets-Sheet 1 INVENTOR h. 14/. Vl/EXEL'L '1 w awrJw- ATTORNEYS Oct. 17, 1967 Filed Jan. 14, 1965 H. W. WEXELL APPARATUS AND KNIFE FOR THE PRODUCTION OF WOOD CHIPS FROM LOGS 4 Sheets-Sheet 2 INVENTOR H. W Wa /v54 4 ATTORNEYS Oct. 17, 1967 H. w. WEXELL 3,347,291

APPARATUS AND KNIFE FOR THE PRODUCTION OF WOOD CHIPS FROM LOGS Filed Jan. 14, 1965 4 Sheets-Sheet 3 INVENTOR BY dwam' WM ATTORNEYS Oct. 17, 1967 H, w. WEXELL 3,347,291

APPARATUS AND KNIFE FOR THE PRODUCTION OF WOOD. CHIPS FROM LOGS Filed Jan. 14, 1965 4 Sheets-Sheet 4 ATTORNEYS United States Patent 3,347,291 APPARATUS AND KNIFE FOR THE PRODUC- TION 0F WOOD CHIPS FROM LOGS Harry Wilhelm Wexell, Gavle, Sweden, assignor to Brundell & Jonsson Aktiebolag, Gavle, Sweden Filed Jan. 14, 1965, Ser. No. 425,493 Claims. (Cl. 144-472) This invention relates to woodworking and more particularly to an apparatus for the production of wood chips from logs and also to a multiple unit knife having a plurality of longitudinally spaced cutting components thereon particularly adapted for use in the apparatus and the apparatus of this invention is primarily intended for reducing an entire log to usable chips.

It has been found that the character of chips utilized in the production of wood pulp has a material bearing on the qualtiy of such pulp, particularly as regards the strength thereof and it has further been found that the quality of the pulp is materially improved by utilizing chips in which there is substantially no distortion or displacement of the wood fibers, one with respect to the other.

Heretofore in the production of wood chips, the primary consideration has been the rapid reduction of a log to chip form without any particular concern as to the uniformity of the chips produced with respect to dimensions and also no particular consideration has been given to the matter of preventing distortion or displacement of the fibers in the chips.

Admittedly, some attempts have heretofore been made to produce high quality chips having uniform characteristics, such as uniform width and thickness and also having undistorted fibers and such chips have been produced, at least on an experimental basis, by utilizing a conventional veneer lathe to cut sheets from a log with such sheets being thereafter cut into chip form. The chips produced in this manner result in providing pulp of superior characteristics, but this method of production has no practical utility, since the same is relatively slow, requires both a veneer lathe and apparatus to cut the resulting veneer into chips and furthermore, after the maximum quantity of veneer has been removed from the log, a core remains which must either be discarded or utilized in some other manner.

A further attempt has been made to solve this problem by the provision of a so-called drum chipper which takes the form of a relatively large cylindrical drum mounted for rotation on a horizontal shaft and with cutters projecting from the periphery of the drum. The drum is rotated at a relatively slow speed and logs are forced transversely against the side of the drum which results in the cutting of strips crosswise of the log by the cutters and such cuts are generally parallel to the direction of the fibers in the log. These strips which have a substantially uniform thickness pass through slits into the interior of the drum against the action of centrifugal force and are discharged from the drum through one or both ends. The resulting chips are only uniform as to thickness, the other dimensions being variable and while such chips are superior to the chips previously produced by a conventional chipping apparatus there are serious disadvantages to this type of chipping apparatus, in that for an acceptable production rate the apparatus must be relatively large and, therefore, costly and furthermore, the logs utilized therewith must be of substantially uniform, relatively short lengths and also the power requirements for such an apparatus are relatively large.

It is accordingly an object of the invention to provide an apparatus for the production of wood chips from logs, which apparatus operates to provide a chip of superior characteristics, which chips may be produced at a relatively rapid rate and with minimum power requirement partially due to the fact that chips are'discharged outwardly in a radial direction assisted by centrifugal force.

A further object of the invention is the provision of an apparatus for the production of chips from logs, which apparatus serves to accommodate logs of any length and also over a relatively wide range of diameters.

A still further object of the invention is the provision of an apparatus for reducing an entire log to usable cli'ips of substantially uniform width and thickness.

Another object of the invention is the provision of an apparatus for reducing logs to chips, which apparatus includes a rotatable drum disposed on a horizontal axis with cutters secured to the drum and projecting inwardly thereof and with logs being fed longitudinally into the drum.

A further object of the invention is the provision of an apparatus for the production of chips from logs, such apparatus including a rotatably mounted elongated, hollow frusto-conical drum open at one end, such drum having a plurality of circumferentially spaced longitudinally extending slots therein and with an elongated multiple unit knife secured in each slot and projecting into the interior of the drum chips being discharged radially outwardly through the slots, such discharge being assisted by the action of centrifugal force.

A further object of the invention is the provision of an apparatus for producing wood chips from logs, such apparatus including a rotatably mounted hollow di-um there being a plurality of circumferentially spaced multiple unit knives secured to the drum and projecting inwardly thereof with the cutting components of the knives displaced longitudinally with respect to each other in order to provide successive overlapping cutting edges disposed in helical spiral paths longitudinally of the drum.

A still further object of the invention is the provision of an apparatus for the production of wood chips from logs, such apparatus including a rotatably mounted hollow drum there being a plurality of circumferentially spaced longitudinally extending slots in the drum, each slot serving to receive a multiple unit knife and there being means for removably securing such knives in adjusted position and for permitting convenient removal or replacement thereof.

Another object of the invention is the provision of a multiple unit knife for use in an apparatus for the production of wood chips from logs, such knife including a plurality of cutting components, each component having a shaving edge joined at one end by an angularly related parting edge with the shaving edges of the components on each knife being substantially parallel and arranged in echelon with respect to the lines of parallelism of the shaving edges.

A further object of the invention is the provision of a multiple unit knife for use in an apparatus for the production of wood chips from logs, such knife including a plurality of cutting components, each component having a shaving edge joined at one end by an angularly related parting edge and with adjacent cutting components spaced from each other with the intervening portion of the knife edge being relieved to provide non-cutting portions between the terminal end of a parting edge of one component and the terminal end of the shaving edge of the next adjacent component.

A still further object of the invention is the provision of a multiple unit knife for use in an apparatus for the production of wood chips from logs, such knife including a plurality of cutting components having a shaving edge joined at one end by an angularly related parting edge, the obverse surface of the knife blade which terminates in the shaving and parting edges being corrugated with the lines of corrugation being substantially parallel and extending generally transversely from the point of juncture between the shaving edge and the parting edge of each component.

A further object of the invention is the provision of a multiple unit knife for use in an apparatus for the production of wood chips from logs, such knife including a blade having a plurality of cutting components, each having a shaving edge joined at one end by an angularly related parting edge and in which the blade is formed of corru gated material of substantially uniform thickness.

Further objects and advantages of the invention will be apparent from the following description taken in conjunction with accompanying drawings wherein:

FIG. 1 is a view in perspective showing the drum of an apparatus for the production of wood chips from logs, together with the manner in which the multiple unit knives are disposed in the drum, as well as the manner of feeding a log to the drum to be reduced to chips;

FIG. 2 a fragmentary view in perspective showing the manner in which the multiple unit knives are secured in place in circumferentially spaced slots in the drum shown in FIG. 1;

FIG. 3 a top plan view of a multiple unit knife for use in the chipping apparatus of FIG. 1;

FIG. 4 a front elevational view of the multiple unit knife of FIG. 3;

FIG. 5 a bottom plan view of the knife of FIG. 3',

FIG. 6 a sectional view taken substantially on the line 66 of FIG. 3;

FIG. 7 a front elevational view showing a multiple unit knife formed of corrugated material of substantially uniform thickness;

FIG. 8 a fragmentary view in perspective similar to FIG. 2, but showing the manner in which the corrugated knife of FIG. 7 is secured in the drum;

FIG. 9 a View in perspective showing a wood chip produced by the apparatus and knife of this invention; and

FIG. 10 a transverse sectional view of the chip shown in FIG. 9.

With continued reference to the drawings, there is shown in FIGS. 1 and 2 a hollow drum 10 which may be utilized in an apparatus for producing wood chips from logs, the drum 10, as shown in FIGS. 1 and 2, being hollow and frusto-conical in form by a proper disposition of the cutters in the drum in a manner to be later described, such drum may, if desired, be cylindrical in formation. The drum 10 may be rotatably supported in any suitable manner by a shaft 11 and, of course, suitable mean for driving the drum will be provided.

The drum 10 may be provided with a plurality of circumferentially spaced longitudinally extending slots 12 and such slots may be closed at the end of the drum remote from the shaft 11 by a ring 13 which may be rernovably secured in place by a screw threaded or other suitable fastening means 14. One side of each slot 12 is beveled to provide a knife blade engaging and supporting surface 15. A plurality of ears 16 are provided adjacent the outer edge of the beveled surface 15 and the ears 16 are provided with aligned apertures 17 which serve to receive a rod 18 on which is pivotally mounted a clamping jaw 19 having a beveled clamping surface 20 and clamping screws 21 may be threadedly received in a segmental cover plate 22 which is secured to the outer surface of the drum 10 between each adjacent pair of slots 12 and with one edge 23 of the cover plate 22 overhanging the adjacent beveled surface 15 and as is clearly shown in FIG. 2, the clamping screws 21 engage the clamping jaw 20 and serve to urge the same toward the beveled surface 15. The segmental cover plate 22 may be removably secured to the drum 10 by screw threaded or other suitable fastening means 24. The space between the overhanging edge 23 of the cover plate 22 and clamping jaw 20 may be closed by an elongated closure plate 25 secured to the clamping jaw 19 and overlapping the overhanging edge 23 of the cover plate 22.

A multiple unit knife 26, the structure of which will be later described, is disposed in each slot 12 with the reverse surface of the knife 26 engaging the beveled surface 15 of the drum 10 and with a clamping bar 27 engaging the upper face of the knife 26 and the clamping jaw 19 is urged into engagement with the clamping bar 27 to securely clamp the knife 26 in place in engagement with the beveled surface 15. The knife 26 may be released for adjustment or removal by suitable manipulation of the clamping screws 21.

With particular reference to FIGS. 3 to 6, there is shown therein the structural details of the multiple unit knife 26 and as clearly shown in these figures, such knife may comprise an elongated blade carrying a plurality of cutting components, each of which comprises a shaving or slicing edge 28 joined at one end by an angularly related parting edge 29. All of the shaving edges 28 are substantially parallel and are arranged in echelon with respect to the lines of parallelism of the shaving edges 28. The cutting components provided by the shaving and parting

edges

28 and 29 are longitudinally spaced from each other and the intervening portion 30 between adjacent cutting components is relieved to provide a non-cutting portion between the terminal end 31 of a parting edge 29 and the terminal end 32 of the next adjacent shaving edge 28. The included angle between the shaving edge 28 and the parting edge 29 of each component in the general plane of the blade 28 is obtuse and furthermore, the shaving edge 28 and the parting edge 29 of each component are angularly related with respect to a plane normal to the general plane of blade 28 and the included angle in this plane is also obtuse.

As clearly shown in FIGS. 3 and 4, the obverse surface 33 of the blade 28 is corrugated with the lines of corrugation being substantially parallel and extending generally transversely from the point of juncture between the

cutting edges

28 and 29 of each component and the lines of corrugation substantially bisect the included angle of each component in the general plane of the blade. In this form of cutting knife, the reverse face 34 of the blade 28 is plane and the obverse face 33 and the reverse face 34 are joined at the cutting edges by clearance faces 35 formed to provide acute included angles between the clearance faces 35 and the obverse face 33 of the blade 28.

Again referring to FIG. 2, the surface of the clamping bar 27 engaging the obverse face 33 of the knife 26 is formed complementary to the corrugated obverse face 33 in such a manner as to mate therewith and thereby securely hold the knife 26 in place in engagement with the beveled surface 15 of the drum 10.

With particular reference to FIG. 7, there is shown a somewhat modified form of multiple unit knife in which there is provided a blade 36 formed of corrugated material of substantially uniform thickness and such blade is also formed to provide shaving edges 37 and parting edges 38 which are formed in the same manner and have the same relationship as the corresponding edges of the knife shown in FIGS. 3 to 6 and described above. The corrugated knife shown in FIG. 7 is secured in the slot 12 of the drum 10 in exactly the same manner as described above in connection with the knife having a plane reverse face and with particular reference to FIG. 8, it will be seen that whereas as shown in FIG. 2, the beveled surface 15 is flat, in FIG. 8 the beveled surface 3 9 is corrugated to correspond to the beveled reverse face 40 of the corrugated knife 36, and, therefore, the corrugated beveled surface 39 will mate with the beveled reverse face of the knife 36 and securely hold the same in position in the drum 10.

With particular reference to FIG. 1, the interior surface of the drum 10 may be provided with spiral grooves 41 which, in effect, form continuations of the shearing edges 28 and parting edges 29 of the cutting component of the knife 26 and such grooves 41 provide clearance spaces for these cutting edges on the interior of the drum 10. The adjacent knives 26 disposed in the grooves 12 of the drum are displaced longitudinally with respect to each other a distance less than the distance between adjacent cutting components to provide successive overlapping cutting edges disposed in helical spiral paths longitudinally of the drum 10 and by reason of this disposition of the knives 26 when a log 42 is fed longitudinally into the open end of the drum 10 in the direction in which the axis of the log 42 is substantially parallel to the shearing edges 28 of the knives 2-6 upon rotation of the drum 10 a succession of helicoidal chips 43 as shown in FIGS. 9 and 10, will be removed from the log 42 with the chips 43 being substantially in the form of a parallelogram in cross section with the surface 44 of the chip 43 being removed from the log 42 by the shearing edges 28 in directions substantially parallel to the fibers of the log 42 and with the side edges 45 of the chip 43 being severed from the logs by the parting edges 29 substantially across the grain of the log 42, thereby preventing crushing of the fibers in the chips 43 to provide a chip of superior quality.

It will be seen that by the above described invention there has been provided an apparatus for producing wood chips from logs, which apparatus is relatively simple in construction and which may be conveniently provided in the form of a portable apparatus for use in the woods to reduce logs to chip form immediately after felling thereof and furthermore, by the provision of a multiple unit knife for use in the drum of the apparatus of this invention, the structure thereof has been materially simplified when compared to prior art apparatus in which a plurality of knives are utilized, each knife providing an individual cutting component. As stated above, the drum 10 as shown in FIG. 1, is frusto-conical in form, but the same may, if desired, be provided as a cylindrical drum in which case the knives 26 are arranged in such a manner as to dispose the shearing edges 28 parallel to the axis of a log 42 to be fed thereto and with such shearing edges 28 arranged in echelon in the same manner as described in conjunction with a frusto-conical drum. Furthermore, the manner of positioning and securing the knives in the drum is relatively simple and permits convenient adjustment or replacement of the knives and the chips removed from the log are discharged outwardly through the slots 12 in a manner whereby such discharge of the chips is assisted by centrifugal force.

It will be obvious to those skilled in the art that various changes may-be made in the invention without departing from the spirit and scope thereof and therefore the invention is not limited by that which is shown in the drawings and described in the specification, but only as indicated in the appended claims.

What is claimed is:

1. An apparatus for the production of wood chips from logs, said apparatus comprising an elongated hollow drum open at one end, means for mounting said drum for rotation about the longitudinal axis, said drum having a plurality of circumferentially spaced longitudinally extending slots in the peripheral wall, a removable ring secured to' said drur'nand closing said slots at the open end of said drum, one side of each slot being beveled to provide a knife engaging and supporting surface, an elongated multiple unit knife having an obverse and a reverse face disposed in each slot with said reverse face engaging said beveled surface, each knife comprising a blade carrying a plurality of longitudinally spaced cutting components, each component having a shaving edge joined at one end by an angularly related parting edge, the shaving edges of the components being substantially parallel and arranged in echelon with respect to the lines of parallelism of the shaving edges, said shaving and parting edges projecting inwardly of the inner surface of said drum with the distance from the shaving and parting edges to the longitudinal axis of said drum progressively decreasing from the open end of said drum toward the opposite end, adjacent knives .being displaced longitudinally with respect to each other a distance less than the distance between adjacent cutting components to provide successive overlapping cutting edges disposed in helical spiral paths longitudinally of said drum, a clamping bar engaging the obverse face of each knife, a clamping jaw pivotally mounted on said drum adjacent each slot, and means for urging each jaw into engagement with each clamping bar to clamp each knife in place in engagement with said beveled surface, whereby upon rotation of said drum and feeding of log longitudinally into the open end of said drum into engagement with said knives, helical chips of substantially uniform thickness will be removed from the log and discharged outwardly through said slots with said shaving edges cutting substantially parallel to the fibers in said log and said parting edges cutting across the fibers at an angle thereto.

2. An apparatus as defined in claim 1, in which the inner surface of said drum is provided with helical clearance grooves, said grooves having substantially the same configuration as the cutting edges of said knife.

3. An apparatus as defined in claim 1, in which the obverse face of said knife is corrugated and the reverse face is plane.

4. An apparatus as defined in claim 3 in which the surface of said clamping bar engaging said knife is formed complementary to the obverse face of said knife to mate therewith and provide clamping engagement over substantially the entire knife contacting area of said bar.

5. An apparatus as defined in claim 1, in which said knife is formed of corrugated material of substantially uniform thickness, said beveled surface being corrugated to mate with the corrugated reverse face of said knife.

6. An apparatus as defined in claim 5, in which the surface of said clam-ping bar engaging said knife is formed complementary to the obverse face of said knife to mate therewith and provide clamping engagement over substantially the entire knife contacting area of said bar.

7. An apparatus as defined in claim 1, in which a segmental cover plate is secured to said drum between each pair of adjacent slots, one edge of each plate overhanging the adjacent beveled surface, the means for urging each jaw into engagement with each clamping bar comprising screw threaded means threadedly received in each overhanging edge of said plate and engaging each jaw.

8. An apparatus as defined in claim 7, in which an elongated closure plate is fixed to each jaw and overlaps the overhanging edge of each cover plate to close the space between each jaw and each cover plate.

9. An apparatus for the production of wood chips from logs, said apparatus comprising an elongated hollow drum open at one end, means for mounting said drum for rotation about the longitudinal axis, said drum having a plurality of circumferentially spaced longitudinally extending slots in the peripheral wall, one side of each slot being beveled to provide a knife engaging and suporting surface, an elongated multiple unit knife having an observe and a reverse face disposed in each slot with said reverse face engaging said beveled surface, each knife comprising a blade carrying a plurality of longitudinally spaced cutting components, each component having a shaving edge joined at one end by an angularly related parting edge, the shaving edges of the components being substantially parallel and arranged in echelon with respect to the lines of parallelism of the shaving edges, said shaving and parting edges projecting inwardly of the inner surface of said drum with the distance from the shaving and parting edges to the longitudinal axis of said drum progressively decreasing from the open end of said drum toward the opposite end, adjacent knives being displaced longitudinally with respect to each other a distance less than the distance between adjacent cutting components to provide successive overlapping cutting edges disposed in helical spiral paths longitudinally of said drum, a clamping bar engaging the obverse face of each knife, a clamping jaw pivotally mounted on said drum adjacent each slot, and means for urging each jaw into engagement with each clamping bar to clamp each knife in place in engagement with said beveled surface, whereby upon rotation of said drum and feeding of a log longitudinally into the open end of said drum into engagement wit-h said knives, helical chips of substantially uniform thickness will be removed from the log and discharge outwardly through said slots with said shaving edges cutting substantially parallel to the fibers in said log and said parting edges cutting across the fibers at an angle thereto.

10. An apparatus for the production of wood chips from logs, said apparatus comprising an elongated hollow drum open at one end, means for mounting said drum for rotation about the longitudinal axis, said drum having a plurality of circumferentially spaced longitudinally extending slots in the peripheral wall, one side of each slot being beveled to provide a knife engaging and supporting surface, an elongated multiple unit knife having an obverse and a reverse face disposed in each slot with said reverse face engaging said beveled surface, each knife comprising a blade carrying a plurality of longitudinally spaced cutting components, each component having a shaving edge joined at one end by an angularly related parting edge, the shaving edges of the components being substantially parallel and arranged in echelon with respect to the lines of parallelism of the shaving edges, said shaving and parting edges projecting inwardly of the inner surface of said drum with the distance from the shaving and parting edges to the longitudinal axis of said drum progressively decreasing from the open end of said drum toward the opposite end, adjacent knives being displaced longitudinally wit-h respect to each other a distance less than the distance between adjacent cutting components to provide successive overlapping cutting edges disposed in helical spiral paths longitudinally of said drum and means to clamp each knife in place in engagement with said beveled surface, whereby upon rotation of said drum and feeding of a log longitudinally into the open end of said drum into engagement with said knives, helical chips of substantially uniform thickness will be removed from the log and discharged outwardly through the said slots with said shaving edges cutting substantially parallel to the fibers in said log and said parting edges cutting across the fibers at an angle thereto.

11. An apparatus for the production of wood chips from logs, said apparatus comprising an elongated hollow drum open at one end, means for mounting said drum [for rotation about the longitudinal axis, said drum having a plurality of circumferentially spaced longitudinally extending slots in the peripheral Wall, an elongated multiple unit knife disposed in each slot, each knife comprising a blade carrying a plurality of longitudinally spaced cutting components, each component having a shaving edge joined at one end by an angularly related parting edge, the shaving edges of the components being substantially parallel and arranged in echelon with respect to the lines of parallelism of the shaving edges, said shaving and parting edges projecting inwardly of the inner surface of said drum with the distance from the shaving and parting edges to the longitudinal axis of said drum 8 progressively decreasing from the open end of said drum toward the opopsite end, adjacent knives being displaced longitudinally with respect to each other a distance less than the distance between adjacent cutting components to provide successive overlapping cutting edges disposed in helical spiral paths longitudinally of said drum, and means to clamp each knife in place in each slot, whereby upon rotation of said drum and feeding of a log longitudinally into the open end of said drum into engagement with said knives, helical chips of substantially uniform thickness will be removed from the log and discharge outwardly through said slots with said shaving edges cutting substantially parallel to the fibers in said log and said parting edges cutting across the fibers at an angle thereto.

12. A multiple unit knife comprising a blade carrying a plurality of cutting components longitudinally spaced from each other, each component having a shaving edge joined at one end by an angularly related parting edge, the shaving edges of the components being substantially parallel and arranged in echelon with respect to the lines of parallelism of the shaving edges, and with the intervening portions of the blade edge being relieved to provide a noncutting portion between the terminal end of the parting edge of one component and the terminal end of the shaving edge of the next adjacent component.

13. A knife as defined in claim 12, in which the included angle between the two edges of each component in the general plane of said blade is an obtuse angle.

14. A knife as defined in claim 13, in which the two edges of each component are angularly related with respect to a plane normal to said general plane of the blade.

15. A knife as defined in claim 14, in which the included angle between the two edges of each of said components in said plane normal to said general plane is obtuse.

16. A knife as defined in claim 15, in which the obverse surface of said blade and which terminates in said edges is corrugated with the lines of corrugation being substantially parallel and extending generally transversely from the point of juncture between the two cutting edges of each component.

17. A knife as defined in claim 16, in which said lines of corrugation substantially bisect the included angle of each component in said general plane of the blade.

18. A knife as defined in claim 17, in which said obverse face of the blade and the reverse face thereof are joined by clearance faces disposed to provide acute included angles between the clearance faces and said obverse face.

19. A knife as defined in clai m18, in which said reverse face of said blade is plane.

20. A knife as defined in claim 18, in which said blade is formed of corrugated material of substantially uniform thickness.

References Cited UNITED STATES PATENTS 3,216,470 11/1965 Nilsson 144-172 X FOREIGN PATENTS 868,208 5/ 1961 Great Britain.

WILLIAM W. DYER, 111., Primary Examiner.

W. D. BRAY, Assistant Examiner.

Claims

1. AN APPARATUS FOR THE PRODUCTION OF WOOD CHIPS FROM LOGS, SAID APPARATUS COMPRISING AN ELONGATED HOLLOW DRUM OPEN AT ONE END, MEANS FOR MOUNTING SAID DRUM FOR ROTATION ABOUT THE LONGITUDINAL AXIS, SAID DRUM HAVING A PLURALITY OF CIRCUMFERENTIALLY SPACED LONGITUDINALLY EXTENDING SLOTS IN THE PERIPHERAL WALL, A REMOVABLE RING SECURED TO SAID DRUM AND CLOSING SAID SLOTS AT THE OPEN END OF SAID DRUM, ONE SIDE OF EACH SLOT BEING BEVELED TO PROVIDE A KNIFE ENGAGING AND SUPPORTING SURFACE, AN ELONGATED MULTIPLE UNIT KNIFE HAVING AN OBVERSE AND A REVERSE FACE DISPOSED IN EACH SLOT WITH SAID REVERSE FACE ENGAGING SAID BEVELED SURFACE, EACH KNIFE COMPRISING A BLADE CARRYING A PLURALITY OF LONGITUDINALLY SPACED CUTTING COMPONENTS, EACH COMPONENT HAVING A SHAVING EDGE JOINED AT ONE END BY AN ANGULARLY RELATED PARTING EDGE, THE SHAVING EDGES OF THE COMPONENTS BEING SUBSTANTIALLY PARALLEL AND ARRANGED IN ECHELON WITH RESPECT TO THE LINES OF PARALLELISM OF THE SHAVING EDGES, SAID SHAVING AND PARTING EDGES PROJECTING INWARDLY OF THE INNER SURFACE OF SAID DRUM WITH THE DISTANCE FROM THE SHAVING AND PARTING EDGES TO THE LONGITUDINAL AXIS OF SAID DRUM PROGRESSIVELY DECREASING FROM THE OPEN END OF SAID DRUM TOWARD THE OPPOSITE END, ADJACENT KNIVES BEING DISPLACED LONGITUDINALLY WITH RESPECT TO EACH OTHER A DISTANCE LESS THAN THE DISTANCE BETWEEN ADJACENT CUTTING COMPONENTS TO PROVIDE SUCCESSIVE OVERLAPPING CUTTING EDGES DISPOSED IN HELICAL SPIRAL PATHS LONGITUDINALLY OF SAID DRUM, A CLAMPING BAR ENGAGING THE OBVERSE FACE OF EACH KNIFE, A CLAMPING JAW PIVOTALLY MOUNTED ON SAID DRUM ADJACENT EACH SLOT, AND MEANS FOR URGING EACH JAW INTO ENGAGEMENT WITH EACH CLAMPING BAR TO CLAMP EACH KNIFE IN PLACE IN ENGAGEMENT WITH SAID BEVELED SURFACE, WHEREBY UPON ROTATION OF SAID DRUM AND FEEDING OF LOG LONGITUDINALLY INTO THE OPEN END OF SAID DRUM INTO ENGAGEMENT WITH SAID KNIVES, HELICAL CHIPS OF SUBSTANTIALLY UNIFORM THICKNESS WILL BE REMOVED FROM THE LOG AND DISCHARGED OUTWARDLY THROUGH SAID SLOTS WITH SAID SHAVING EDGES CUTTING SUBSTANTIALLY PARALLEL TO THE FIBERS IN SAID LOG AND SAID PARTING EDGES CUTTING ACROSS THE FIBERS AT AN ANGLE THERETO.