US2949946A

US2949946A - Means for producing flakes while cutting a flat surface on wood

Info

Publication number: US2949946A
Application number: US724549A
Authority: US
Inventors: Donald L Johnson
Original assignee: Individual
Current assignee: Individual
Priority date: 1958-03-28
Filing date: 1958-03-28
Publication date: 1960-08-23
Anticipated expiration: 1977-08-23

Description

- Aug. 23, 1960 L. JOHNSON MEANS FOR PRODUCING FLAKES WHILE 4 Sheets-Sheet l CUTTING A FLAT SURFACE ON WOOD Filed March 28, 1958' v IIB .' INVEN TOR.

ATTORNEY D. L. JOHNSON 2,949,946 MEANS FOR PRODUCING FLAKES WHILE cu'r'rmc A FLAT SURFACE on woon Aug. 23, 1960 4 Sheets-Sheet 2 Filed March 28, 1958 ATTORNEY DONALD L. JOHNSON Aug. 23, 1960 D. L. JOHNSON ,949,

MEANS FOR PRODUCING FLAKES WHILE CUTTING A FLAT SURFACE ON WOOD Filed March 28, 1958 4 Sheets-Sheet 3 INVENTOR. DONALD L. JOHNSON ATTORNEY 1960 D. L. JOHNSON 2,949,946

MEANS FOR PRODUCING FLAKESWHILE CUTTING A FLAT SURFACE ON wooo Filed March 2B, 1958 4 Sheets-Sheet 4- Fig: .157 ?.Q

28 7 28 17 2 A 28A mvzsmoa. J E DONALD'L. JOHNSON ATTORNEY United States Patent O "ice MEANS FOR PRODUCING FL'AKES WHILE CUTTING A FLATSURFA'CE ON WOOD Donald L. Johnson,'8'31.Rust Bldg, Tacoma 2, Wash.

Filed Mar. 28 1958, Ser. No. 724,549"

- 6 Claims. (Cl. 144-162) This invention, like that described in my pending application, Serial No. 627,687, filed under date of December 11, 1956, and now Patent Number 2,889,859, and entitled Method and Means for Cutting a Flat Surface on Wood by Producing Wood Flakes from the Material as Removed, and like that described also in my pending application, Serial No. 701,405, filed under date of December 9, 1957, and entitled Wood Flaking and Surfacing Machine," relates to the producing of special wood flakes as the result of the cutting of a desired flat surface longitudinally along a log or timber or other wood mass; and the wood ,flaking and surfacing means employed in the present invention is an additionally improved means by which the method described in said application Serial No. 627,687 can be carried out, and is a further improvement in thecutter head and cutting knives described in said application Serial No. 701,405.

An object of this present invention is to providean improved and simplified cutter head assembly for producing the desired wood flakes and :for cutting a desired flat surface on wood, in which the cutterhead assembly will include improved knives removably mounted in the cutter head.

A more specific object of this invention is to provide an improved cutter head equipped with knives which are removably mounted therein by improved and more reliable locking means.

2,949,946v Patented Aug. .23, 1960 Fig. '4 is a side elevation of one of the cutting knives entirely removed from the cutter head;

Fig. 5 is an elevation showing the opposite side face of the same knife;

Fig. 6 is an outer end view of the knife showing its cutting edge and cutting spur, .this view being taken on line 6-6 of Fig. 4; I V

Fig, 7 is a side view of one lateral edge of the knife taken on line 7-.7 of Fig. v4; p I

Fig. 8 is ac similar view showing the opposite lateral edge of the knife, taken on line 8+8 of Fig. 4;

Fig. 9 is a fragmentary section through one of the knives :and its slot in the cutter head, this section being taken on line 9--9of .Fig. 3, but drawn to alarger scale;

Fig. 10 is a similar sectionon line IO-1015f Fig. 3;

Fig. 11 is a view of the locking wedge plug by itself which is shown in operating position with respect to the knife in Fig. 10, this view showing the wall of the locking wedge .plug which engages the knife and this showing the side of the plug which is face towards the right in Fig. 10;

.Fig. 12 an exploded sectional elevation of .the lock ing wedge plug v:positionedasiin Fig, 10 but showing the two members of the same separated;

Fig.13 is apl'anview of the locking wedge [plug taken online 13?13 of Fig. 12, but drawn to twice the size A related object of the invention is to provide a cutter head in which the knives .can be readily adjusted to suit changed operating conditions.

Another object is to provide improved knives-for a cutter head assembly of the type described in the above mentioned applications, which knives will be simpler in construction, less costly to produce, andeasier to sharpen and maintain in service.

A further object of this invention is to provide improved knives of unique construction, suitable for use in such a cutter head of .a wood flaking and surfacing machine, whereby each knife will present two or more cutting edges in place of a single cutting :edge, withoutany change being required in the cutter head itself, thereby resulting in more cutting edges for the same diameter cutter head and thus enabling the depth of cut by the cutter head assembly to be increased witha corresponding increase in capacity for wood flake production.

These objects and other incidental advantages are attained with the employment of knives, .adjustably rand removably mounted in :the cutter head, as hereinafter briefly described andtexplained'with.referenceto the accompanying drawings.

In the drawings:

Fig. 1 is an elevational view of the working face :of the cutter head assembly illustrating one arrangement of the improved knives in the same;

Fig. 2 is a fragmentary side view' of :the cutter head assembly taken on line 2-1 of Fig. 1;

Fig. 3 is an extended and developed side view of the cutter head assembly showing that .portion .indicatedlby. line 3-3 in Fig. 1;

for the sake of clarity;

.Fig; ,14 is a m-elevation, more J01 less diagrammatic, showing the cutter head operating under a hood, indicating in broken lines the two helical-spiral courses of the cutting edges of the knives and illustrating the cutting of a flat surface .on a log;

Fig. 315 is an .BIWZIJfiOILShOWiIIg one face of .amodified form of cutter head knife in which the knife is provided with two. separate cutting edges;

Fig.1116 is an .elevation showing the opposite face of the sameknife;

Fig. 17 is ;a view, partly diagrammatic, of the working face ,of :the cutter head assembly, formed inaccord-ance with the Present invention, 'but showing plural-edged knives, of the type illustrated in Figs. 15 and '16, substitutcd for the single=edged knives shown inFig. =1:

Fig. 18 'is .a fragmentary .and partly diagrammatic side elevation of the .cutterhead assembly of Fig. 17 taken on line 13-18 of Fig. '17; 4

Fig. 19 is .a diagrammatic representation of the :cutter h a of Fig. :1 with the two identical peripheral portions and :with single-edged knivesinieach portion forming two radially-retreating, axially-advancing knife courses;

Fig. 20 is a similar diagrammaticrepres'entation of the cutter head of Fig. 17,:havingdonble-edged knives;

Fig. 21 is a siniilarir'epresentation .of .a cutter head having three Iidentical peripheral portions with doubleedged knives;

.Fig. .122 :is a similar representation @of a-cutter head having two identical peripheral portions ibut with tripleedged .knives; and

Fig. 23 is a diagrammatic plan view lookingdownward-lyxon 'theparts of Fig. 14.

Referring first .to Figs. 1, :2 and-3, the cutter head 10 which is so arranged as .to be driven in the direction indicatcd by the arrow :X, and thus .dr iven counterclockwise as viewed inFig. :1, has its periphery formed with oppositely-positioned nolute portions A andzB .(Fig :1), each extending halfway around the periphery and each having a .cons'tantly decreasing radius, the radius thus decreasing clockwiseor in the direction opposite from the .directiontcf rotation :of the cutter head. Identical,

knife bodies to zbeplaced therein. ;However,:.these slots,

instead of extending in radial planes perpendicular to the Working face of. the cutter head, extend in'planes inclined at a suitable acute angle, for example at an angle of 30, with respect to the plane of the working face of the cutter head or with respect to a plane perpendicular to the cutter head .ax-is. These inclined, equally spaced andidentical slots terminate either .onthe working face of the cutter head or on the other or outer face of the cutter head, or, if preferred, depending upon the thickness of the cutter head, these slots may extend obliquely from one face of the cutter head to the other on the cutter head periphery.

' The shapeyand construction of the knives 12, which are shown mounted in these peripheral, obliquely-extending slots 11 in Figs. 1, 2 and 3, will be understoodclearly from'Figs. 5 'to 8 inclusive. These knives'are substantially rectangular bars of steel with a beveled surface 13 on one end which provides the cutting edge 14 atthat end. However, along one side of this-beveled ing" position with the knife 12, the serrations on the plug face 22 being brought into engagement with the surface '13, a wedge-shaped raised portion is left so as i to form a cutting spur 15 with a sharp, more steeply sloping, cutting edge 15', which edge is located in the same plane as the longitudinalside edge of the knife body. The function of this spur on the knife blade will be explained later. i V

The body portion of each knife 12 has longitudinally extending serrations 16, or sharp ridges and grooves, 011 that portion of one face (which is the trailing face with respect to the direction of rotation of the cutter head) which is positioned in the knife slot. The oppo site face of the knife:body, along the same edge, is tapered slightly towards that edge and this tapered surface 17 has similar serrations but theserrations are perpendicular to the edge instead of beingparallel to the edge. The purpose of these two opposite sets of serra tions is to enable the blade to be firmly but adjustably secured in its slot 11 of the cutterhead. One side wall ofeach slot 11 in the cutter head' is provided with serrations 18 '(Figs. 9 and 10) to cooperate with the serrations 16 on the body of the knife. The inner portion of the opposite wall of the slot will be spaced a distance from the adjacent side face of the knife when the knife is in place in the slot since the width of the slot '11 is greater than the thickness of the knife body. The upper portion of this opposite wall is cut back as shown at 1113 in Figs. 9 and 10 to providea passageway 11A for the wood flakes. A cylindrical recess 19 (see Figs. 1, 3,"'and 10), which extends into the cutter head beyond the depth of the slot 11 also cuts into this opposite wall. dicular tothe bottom wall'of the slot and perpendicular to the cutter head This cylindrical recess 19 accommodates .a locking wedge plug 20 (shown-in- Figs. 10 to 13 inclusive) byIwhich the knife is securely locked in place in its slot 11. i l i The locking wedge plug 20 consists of a main body 20Aand-a set :screw 20B which'is adjustable in a threaded channel 21 (Fig. 12) in themain body 20A. The main body 20A is in the shape of a cylinder except that one side of the cylinder is cut away so'as to form a fiat inclined surface 22 having a slope with respect to the axis of the body 20A which corresponds to the taper on the serrated tapered surface17 of the knife body, and this inclined surface 22 of the plugis provided with serrations to correspond to and engage with the serrations on the tapered'surface 17 of the knife body.

The set screw 20A of the plug has a socket 23 (Fig. 13), preferably hexagonal, so as to enable the set screw to be turned in the plug by inserting a hexagonal or splined wrench.

When the knife 12 is set in desired position in the slot 11, with the serrations 16 of the knife body engaging the serrations 18 of the slot wall, and with the locking wedge plug 20 in lowered position in its recess 19, the set screw 20B is turned so as to force the serrated tapered face 22 of the plug bodyZUA into tight wedg The of this cylindrical recess 19" is perpencorresponding serrations 17 .on the body of the knife. It will be apparent now from Figs. 3 and 10 that under such conditions the knife 12 will be firmly secured in place in its slot, since the double set of engaged serrations prevent any possibility ofrnovement of the knife relatively with respect tothe slot and cutter head. Also it will be apparent that, by releasing the set screw 20B and thus enabling the plug body 20A to be moved inwardly and out of engagement with the knife body, the knife 12 can be removed entirely from its slot or can be given a slight adjustment, longitudinally with respect to the slot and knife body, in the cutter head. The

resharpening of the knives from time to time will necessitate a slight change in the relative positioning of the knives in their slots, but this means of mounting the knivesenables-suchslightchanges in positioning tobe accomplished readily. These are important features in the improved and simplified construction of the knives and of their mounting in place in the cutter head.

. In the cutter head illustrated in Figs. 1, 2 and 3, the two volute peripheral portions A and B of the' cutter head 10 are each provided with eight knife slots 11 and aknife 12 secured in each slot by the means previously described, the knives in each of these volute peripheral portions A and B being numbered from 1 to 8 in Fig. 1. While the slots 11 and the body portions of the knives 12 all slope obliquely with respect to the plane of the outer or working faceof the cutter head, the cutting edges 14 of the eight knives in each of the two peripheral portions A and B of the .cutter head extend in planes which are perpendicular to the axis of the cutter head and thus in planes which are parallel to the plane of the outer or working face of the cutter head. Furthermore these parallel planes, in which the cutting edges of the knives are located, intersect (the cutter head axis successively at equally spaced distances along the axis in a direction extending towards the work or towards the outer or working face of the cutter head. Thus, since the cutting edges of the eight knives in each of the volute peripheral portions A and B are positioned progressively forwardly towards the work while these knives and slots are located in volute peripheral portions the radius of which decreases the knives extending outwardly from these peripheral portions, the cutting edges of the knives in each of the two groups are located in a helical-spiral course, extending in a direction opposite the direction of rotation of the cutter head, constantly approaching the axis of rotation of the cutter head. and constantly progressing forwardly longitudinally with respect to the rotational axis, in the nature of a helix. Thus the cutting edges of the eight knives in each of the two groups can be described as located in a radially-retreating, axially-advancing course. Consequently the cutting edges of the knives in the cutter headcorrespond to the cutting edges of the knives in the cutter heads described in the previously mentioned pending applicationsflThe cutting edges of the correproduce the desired'w'ood flakes during the cutting of this surface, while the log is moved in a direction perpendicular to the axis of the rotating cutter head. Assuming in this illustration that the effective cutting edge in each knife is 1 inches longiand that each peripheral portion Aland B, thus each radially-retreating, axially-advancing knife course, approaches the axis of the cutter head 1% inches during 180 rotation'of the cutter head, longitudinalmovement of the log 1 inchesduring each 180 rotation of the cutter .head will result in wood flakes of the maximum length being cut with thecutter head knives.

thickness of the individual flakes will be determined by the difference in level between the cutting edges of thesuccessive knives in each of the radially-retreating, axially-advancing knife courses. Since the improved and simplified knife construction and the improved method and means for mounting the knives in their slots enable the knives to be adjusted in the slots, the difference in level between the cutting edges of the successive knives can' be increased if thicker flakes are desired, and vice versa. In any arrangement this difference in level between the cutting edges of the successive knives must however be made the same throughout both knife courses.

As the knife edges slice through the wood to produce the wood flakes the severing of the spiral ends of the flakes from the body of the wood is facilitated by the spurs 15 (Figs. 2, 3,4 and 7) carried at'the outer edge of the cutting edges of the knives since the spurs extend down further into the wood and thus cut the ends of the flakes loose instead of having these spiral ends of'the flakes merely break loose from the body of the wood, and consequently the employment of such spurs is of special importance particularly in the cutting of thicker flakes since the spurs prevent the possibility of such flakes being severed from the wood body with broken or frayed ends, instead of with clearly defined cut ends. In the arrangement illustrated in Figs. 1, 2 and 3 all of the knife edges accordingly, with the exception of the last knife in each course, are formed with cutting spurs such as that shown at 15 in Fig. 4. Since the last knife of each course cuts the final surface produced on the mass of wood, a spur on the last knife in each course would mar the resulting straight cut surface and consequently the spur would be omitted from the last knife.

"From Figs. 4 to 7 inclusive it will be apparent that the sharpening of the individual knives (and also the sharpening of their spurs), is a relatively simple matter when the knives are removed from their slots in the cutter head. Since the knives can be adjusted longitudinally in their slots in the cutter head, as previously explained, the knives can continue to be used even after being resharpened several times. Preferably each of the slots 11 of the cutter head will have a special marking indicating the position of the cutting edge of the knife according to a predetermined and established difference in level between successive knife cutting edges, and such marking will thus facilitate the setting of the knives in place after their removal for resharpening or in the event of replacement.

Thus far each knife has been described as having a single cutting edge, such as the edge 14 of the knife 12. I have found, however, that it is possible and practical also to form each knife with two or even more separate cutting edges. Figs. 15 and 16 show opposite side elevations of a knife 26 formed with two

separate cutting edges

27 and 28. This knife, with the stepped cutting end, resembles to considerable extent the single-edged knife 12 previously described. Thus the body of this knife has longitudinally-extending serrations 29 (Fig. 15) on one face near one lateral edge (corresponding to the serrations 16 of the knife 12 shown in Fig. 4), and the opposite face of the body of the knife has a tapered portion 30 (similar to the tapered portion 17 of the knife 12 shown in Fig. and at least half of this tapered portion 30 has serrations 30' which extend perpendicular to the lateral edge of the knife body.

In order to provide the two

separated cutting edges

27 and 28 the end of the body portion of this modified knife is made in stepped formation and the stepped portions are each then given a beveled face, as shown at 27A and 28A in Fig. 15, so as to form the two desired

cutting edges

27 and 28. The effective length of the two cutting edges is made substantially the same, that is to say, the cutting edge 28 is substantially the same length as the working portion of the cutting edge 27, indicated at C in Figs. 15 and 16, which is the portion of that cutting edge which extends beyond the cutter head periphery when the knife is secured in its slot in the cutter head. These cutting edges extend in planes which are perpendicular to the cutter head axis. Both cutting

edges

27 and 28 preferably are provided with cutting

spurs

27B and 28B respectively, similar to the spur 15 on the knife 12 previously described (except that the cutting spur 27B on the edge 27 is omitted in the case of the last knife in each helical spiral course).

When each knife 26 is formed in this way, with two separate cutting edges, the body of the knife will be longer and wider than in the case of the knife 12 having only one cutting edge of the same size. Consequently for mounting these larger knives in their cutter head grooves I consider it preferable to use a pair of locking wedge plugs for each knife instead of only a single locking wedge plug. These pairs of locking wedge plugs are indicated at 31 and 32 in Fig. 18 for each of the blades 26. These locking wedge plugs are the same as the locking wedge plug 20 (Fig. 12) previously described. However, when a pair of locking wedge plugs are to be used for each blade, it is preferable to omit the serrations 30' (Fig- "16) from approximately one-half of the tapered surface 30 so as to avoid any possible difiiculty in always having the serrations of both plugs come into exact engagement with the same series of serrations on the tapered surface of the knife, and the engagement of a single wedge plug with such serrations is sufficient to prevent any longi tudinal movement of the knife in the slot against such serrations engagement.

Figs. 17 and 1-8 show a cutter head 10' having two volute peripheral portions A and B, similar to cutter head 10 in Fig. l, and similarly having equally spaced, obliquely sloping knife slots. It will be noted that the two

cutting edges

27 and 28 of each knife in this arrangemerit constitute in effect separate cutting knives located approximately 360 apart in separate radially-retreating, axially-advancing courses. Thus the knife course marked D in Fig. 17 begins with the cutting edge 28 of the first knife 26 while the cutting edge 27 of that same knife constitutes part of the second knife course E which begins later on the cutter head. In this particular arrangement as illustrated there are two radially-retreating, axiallyadvancing knife courses these being 180 apart on the cutter head, but the use of the pair of separated or stepped cutting edges on each knife enables each of the two knife courses D and E to extend for approximately 360 instead of only for 180. In other words, there are twice as many cutting knife edges on the same cutter head, which enable the cutter head to make a deeper cut in the wood surface with each revolution of the cutter head and consequently to produce a greater number (in this case twice as many) of the desired identical special wood flakes with each revolution.

Instead of having the cutter head provided with two volute peripheral portions, each having the same number of slots for the double-edged knives, it would also be possible to provide the cutter head with a larger number of identical volute portions and consequently similarly to increase the number of radially-retreating, axiallyadvancing courses. Fig. 19 is a diagrammatic represen tation of the cutter head of Fig. 1 having two volute peripheral portions A and B with two radially-retreating, axially-advancing knife courses each extending for 180. Fig. 20 is a corresponding diagrammatic representation of the cutter head of Fig. 17, similarly having two volute peripheral portions but, due to the use of the two-edged knives as previously explained, having two radially-retreating, axially-advancing knife courses D p and E each extending for 360.

- Fig. 21 illustrates diagrammatically howa cutter head could have three volute peripheral portions and, with the use of two-edged knives, have three radially-retreating, axially-advancing knife courses F, G and H each extending for 240.

Fig. 22 illustrates further how a cutter head with two volute peripheral portions, by using knives with three separate stepped cutting edges, in place of the two-edged knife 25 of Figs. 15,and 16, would have two radiallyretreating, axially-advancing knife courses M and N each extending one and one-half times around the cutter head.

Thus, in the carrying out of this invention with a cutter head having volute peripheral portions, the number of radially-retreating, axially-advancing knife courses will be equal to the number of volute peripheral portions and whether each course has the same length as a volute portion or has two or more times the length of each volute portion will be governed by the number of separate cutting edges provided in the special knives employed. In any case, however, the cutting edges in all the knives on a cutter head must be the same effective length, the successive knife edges in each course must be spaced the same distance apart, and the difference in level between successive knife edges in each course must be the same for proper operation of the cutter head and for producing the desired identical wood flakes.

I claim:

1. In a rotating cutter head for a wood flaking and surfacing device, a plurality of slicing knives secured on said cutter head and extending from its periphery, the periphery of said cutter head provided with equally spaced, substantially rectangular mounting slots for said knives, said slots inclined forwardly in the direction of rotation of said cutter head and extending in planes all having the same angularity with respect to the cutter head axis, each of said knives having a body with a thickness less than the Width of said slots, the forward end of each knife body beveled to form a cutting edge, the cutting edges of said knives extending perpendicular to said cutter head axis, the trailing face of each knife having longitudinally-extending serrations, the adjacent wall of each slot having corresponding engaging serrations, the leading face of each knife body having a slight transverse taper and having serrations extending laterally on said tapered portion, a locking wedge plug for each knife, each slot having a recess for said wedge plug, each wedge plug having a face adapted for engagement with said latter mentioned tapered portion on the knife body, means for releasably securing said wedge plug in locking engagement with the knife body, the periphery of said cutter head being so formed that said slots will be arranged in a series with the radial distance of said slots from the axis of said cutter head decreasing in said series in the direction opposite from the direction of rotation of said cutter head, and said knives so positioned in said slots that said cutting edges will also be located in an axially-advancing course throughout said series.

2. In a rotating cutter head for a wood flaking and surfacing device, a plurality of slicing knives secured on said cutter head and extending from its periphery, the periphery of said cutter head provided with equally spaced, substantially rectangular, mounting slots of uniform width for said knives, said slots inclined forwardly in the direction of rotation of said cutter head and extending in planes all having the same angularity with respect to the cutter head axis, each of said knives comprising a substantially straight bar with a thickness less than the width of saidslots, the forward end of each knife bar beveled to form a cutting edge, the cutting edges of said knives extending perpendicular to said cutter head axis, the trailing face of each knife bar having longitudinally-extending serrations on that portion of the face within the knife slot, the adjacent wall in each slot having corresponding engaging serrations, the

leading face of each knife bar having a slight transverse taper on the portion within the knife slot and having serrations extending'laterally on said tapered portion,'a locking wedge plug for each knife, each slot having a recess for said locking wedge plug, each locking wedge plug having a serratedface adapted for engagement with saidlatter mentioned lateral serrations on; said-tapered portion on the knife bar, means for releasably securing the, locking wedge plug in locking engagement with the knife bar, the periphery of said cutter head b eingsso formed that slots will be arranged in a plurality of identical series with the radial distance of said slots in each series from the axis of said cutter head decreasing in the direction opposite from the direction of rotation of said cutter head, and said knives in each series soposiv tioned insaid slots that said cutting edges willalso-bo located in an axially-advancing course in each series, 5

3. Ina rotating cutter head for a woodflaking andsurs facing device, a plurality of slicing knives secured on said cutter head and extending from its periphery, the periphery of said cutter head-provided with equally, spaced mounting slots for said knives, said slots inclined forward-, ly in the direction of rotation of said cutter head and ex tending in planes all havingthe same angularity with respect to the cutter head axis, each of said knives having a body substantially rectangular in cross section with athickness less thanthe width of said slots, the forward end of eachknife body beveled to form a cutting edge, the cutting edges of said knives extending perpendicul ar to said cutter head axis, means for removablynand ad;- justably locking each knife in its slot, the periphery of said cutter head being so formed that said slots will be arranged in a series with the radial distance of said slots from the axis of said cutter head decreasing in said series, in the direction opposite from the direction of rotation of said cutter head, and ,said knives so positioned in said,

- slots that said cutting edges will be located in an axially-,

advancing course throughout said series. p

4. In a rotating cutter head for a wood flaking and surfacing device, a plurality of slicing knives secured .on said cutter head and extending from its periphery, the, periphery of said cutter head provided with equally spaced, substantially rectangular, mounting slots forsaid, knives, said slots inclined forwardly inthe direction of rotation of said cutter head and extending in planes all having the same angularity with respect to the cutterhead axis, each of said knives comprising substantially a, straight bar witha thickness less than the width ofsaid, slots, the forward end of each knife bar formed into a pair of stepped cutting .edges, the cutting edges of said knife bars all extending perpendicular to said cutter head axis;

means for removably locking each knife bar in its slot,

the periphery of said cutter head being so formed that said. slots will be arranged in a plurality of identical series with the radial distance of said slots in each series from theaxis of said cutter head decreasing in the diretnion,

opposite from the direction of rotation of said cutterhead, and the knife bars in the slots in each series being sopositioned in said slots that the consecutive cutting edgesof-said knife bars will be located in axially-advano, ing courses. i I J 5. ha rotating cutter head fora wood flaking and, surfacing device, a plurality of slicing knives secured on said cutter head and extending from its periphery, the periphery of said cutter head provided with equally, spaced, substantially rectangular, mounting slots of uniform width for said knives, saidv slots inclined forwardly in the direction of rotation of said cutter head andextend: ing in planes all having the same angularity with respect to the cutter head axis, each of said knives having a body. substantially rectangular in cross section with a thickness: lessjthan the width of said slots, the forward endof each knife body formed into a plurality of parallel stepped cutting edges, said cutting edges of said knives extending perpendicular to said cutter head axis, the trailing face? of each knife body having longitudinally-extending seri s 1 t PQr Qav th ace i h afi fe sl s,

the adjacent wall in each slot having corresponding engaging serrations, the leading face of each knife body having a slight transverse taper on the portion within the knife slot and having serrations extending laterally on said tapered portion, a locking wedge plug for each knife, each slot having a recess for said locking Wedge plug, each locking wedge plug having a face adapted for engagement with said latter mentioned tapered portion on the knife body, means for releasably securing said locking wedge plug in locking engagement with the knife body, the periphery of said cutter head being so formed that said slots will be arranged in a plurality of identical series with the radial distance of said slots in each series from the axis of said cutter head decreasing in the direction opposite from the direction of rotation of said cutter head, and the knives in the slots in each of said series being so positioned in said slots that the consecutive cutting edges of said knives will be located in axially-advancing courses.

6. The combination set forth in claim 1 with the forward beveled end of each knife having a cutting spur along the outer edge of the beveled face.

References Cited in the file of this patent UNITED STATES PATENTS