AU2007202617A1 - High speed planer head - Google Patents

Description

P/00/01 I Regulation 3 2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT

(ORIGINAL)

Name of Applicant: Key Knife, Inc. of 19100 SW 125th Court, Tualatin, Oregon 97062, United States of America Actual Inventors: Address for Service: Invention Title: Bradley R. STAGER DAVIES COLLISON CAVE, Patent Trademark Attorneys, of 1 Nicholson Street, Melbourne, 3000, Victoria. Australia Ph: 03 9254 2777 Fax: 03 9254 2770 Attorney Code: DM "High speed planer head" The following statement is a full description of this invention. including the best method of performing it known to us:- P 'OPER .SS'JnJu C S7 p mdo 00 This and/or that invention relates to a wood-cutting knife, such as for use in commercial manufacturing of construction lumber and finished wood products.

C 5 The finish on construction lumber, such as cut from logs into 2 X 4, 2 X 6, 2 X 12, and 4 X 4 nominal dimensions, has become increasingly important as a result of the trend for such construction lumber to be sold in retail outlets, such as the large home improvement chain stores, to "do-it-yourself' (DIY) consumers. While construction lumber is typically covered with sheet rock or gypsum board and so is not visible in finished construction, DIY consumers often select and purchase construction lumber primarily on the basis of surface finish. Accordingly, well finished construction lumber can command a premium price, and construction lumber that is not well finished may be difficult to sell.

Commercial planer heads include a plurality of elongate knives spaced circumferentially on a cylindrical hub rotating at high speed. The elongate axes of the knives are typically, but not necessarily, aligned with the axis of rotation. The wood travels relative to the head in a direction perpendicular to the axis of rotation of the hub, the knives cutting a surface on the wood. The resulting surface finish is affected by a number of factors, the extent to which the planer head is in balance, the density of knives on the planer head, the speed of rotation, the speed of travel of the wood, and the ;Z Lbit" o"i ;ii nm 2s1 to t:iriently' r.1p 1aay:oiri theI "LI 12', tac S as IQ 00 beineo cut Standard pra,,ctice -,r.ovtdes tor statjcaljy LalLanci the kniv\es and km fec asscem-blecs IND carrted by, the hub as wtll as dyniamically balancinmu the hub and the_ shalft to hic)h the is attached (or with whtch the hub :s integraflvy formeld) The, speed of -rotation of the head is set as h igh as prctand thec speed of travel of the wood is set as hipub as possible whi1111 s:ill providine accepb ie surface Finish, to increase the speed of p-oducticn, Someic "chirn marks" occurII as a result of chips remaining on the cuttinig S~irface as the wood is becing cut a-nd have been accepted in the prior artL With a given degree of balancing and speed of rotation of the., planer hea-d, increasing the speed of wood travel to obtain further efficiecyC inereases will d-crea,:se- :he qluality" Of the- surface finish, and it would he adV3a ICoiis either to be abie to tncrcase ile, speed v.'h i c majintainmug the quality of sir face finish, Or miai a: n the speed and i mpro vc*0% the' G.uality of tie surIfaIc finish I 5 One me1ans for increasing the Sur faLce quality giv~en the I hmi atotis nioted ao'.,c !s to increase the frequeincy of*c.utting by rncr-casing the denisity of knive-s on the jplaner head Part1CIcutarly, theI parlle1-l and circumWrferen-rtially distributcd cattinc- tedges of the knives shoul:d be spaced as ciose touthe r as possible. H-oweve, r, ea-ich knife- must be removable so that the knilfe can be sharpened or- replaced. The knive ts are typically cli'am-ped ii k:ife asseniblies by scr-ews The screwvs gmay bear on a block of metial calie-d a -'iL'ib that i: tu:rn bears on he knife, the end of the screw~ miay bear directly on the knfie, or the screwv may extend into a collar that wedc s a eai ust the knife In all] cases, the constr-uction g1 -3- POPLR'SAS. 00 methodology places limits on the potential for increasing the density of the knives.

Typically, prior art knives have a straight cutting edge and one or two radiused or semi-circularly curved cutting edges at respective ends of the straight cutting edge. Where Sonly one curved cutting edge is employed, the knives are alternated in upside-down and C 5 right-side-up position so that two knives together cut respective opposite corners of the r-' wood and each knife cuts the straight face of the wood so that the straight face of the wood C is twice cut. In either case, a straight cutting edge is physically merged with a curved cutting edge. In a process known as "jointing," used for sharpening the knives as the knives are installed in the planer head and as the head is rotating, wherein a fixed stone is introduced against the rotating knives, vhat is known in the art as "relief' is lost for the outer portions of the curved cutting edges. This lack of relief results in hammering the wood at the comers, degrading surface finish.

Another problem in the prior art is adjusting the planer head between cutting an article of wood from green wood stock to cutting an article of the same nominal size from dry wood stock, and vice-versa. This has required replacing the complete planer head, which is costly.

According to one aspect of the present invention, there is provided a wood-cutting knife comprising curvilinear cutting edges, where is greater than 2, spaced apart from one another with 360/n degree rotational symmetry, the knife having a planar front side, a spaced apart, planer back side and a beveled face connecting said front and back sides at respective outer peripheral contours thereof, wherein the outer peripheral contour of said front side includes one of said cutting edges, wherein, in a cross-section of the knife taken in a plane perpendicular to the plane of said front side and to the peripheral outer contour thereof, said beveled face defines an attack relief angle with respect to said plane, wherein said attack relief angle is in the range of 25-40 degrees.

Preferably, the cutting edges are concave and semi-circular. Preferably, 4.

Preferably, the knife includes, associated with at least one of said cutting edges, substantially linear outer perimeter portions that provide respective alignment reliefs with respect to lines tangent to the ends of said at least one of said cutting edges. Preferably, the reliefs define alignment angles of relief between said lines and said outer perimeter P 'OPER'SASJin Ji r 2fi7'9 Sp- dlu /u2!'tL 7 00 a -4portions that are at least about 20 degrees.

SAccording to a further aspect of the present invention, there is provided a wood- Scutting knife comprising at least two spaced apart, concavely curvilinear cutting edges, C- 5 wherein respective lines bisecting said cutting edges extending from respective points of intersection therewith to respective centers of curvature thereof diverge from one another, C<1 the knife having a planar front side, a spaced apart, planer back side and a beveled face connecting said front and back sides at respective outer peripheral contours thereof, wherein the outer peripheral contour of said front side includes one of said cutting edges, wherein, in a cross-section of the knife taken in a plane perpendicular to the plane of said front side and to the peripheral outer contour thereof, said beveled face defines an attack relief angle with respect to said plane, wherein said attack relief angle is in the range of 25-40 degrees.

Preferably, the cutting edges are semi-circular. Preferably, the attack relief angle is constant over said beveled face. Preferably, the knife includes, associated with at least one of said cutting edges, substantially linear outer perimeter portions that provide respective alignment reliefs with respect to lines tangent to the ends of said at least one of said cutting edges. Preferably, the reliefs define alignment angles of relief between said lines and said outer perimeter portions that are at least about 20 degrees. Preferably, the knife has four spaced apart, concave semi-circular cutting edges. Preferably, the cutting edges are spaced apart from one another with 90 degree rotational symmetry.

The present invention will now be described, by way of non-limiting example, with reference to the accompanying drawings, in which: Figure 1A is side elevation of a prior art planing apparatus.

Figure 1B is a top view of the planing apparatus of Figure I A.

Figure 2 is an end view of a prior art planer head for use in the apparatus of Figures lA and 1B.

Figure 3 is more detailed end view of the planer head of Figure 2.

P OPER'SA S' Jn. J l(7".ii Spa. c o

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00 \D 5 C-A 10 Figure 4A is a pictorial view of an alterative prior art planer head.

Figure 4B is a pictorial view of two collars used in the planer head of Figure 4A.

Figure 5 is an end view of a face-cutting planer head.

Figure 6 is more detailed end view of the planer head of Figure Figure 7 is a pictorial view of a preferred knife for use in the planer head of Figure Figure 8A is a cross-sectional view of an unfinished article of lumber.

Figure 8B is a cross-sectional view of the article of lumber of Figure 8A in a finished condition.

Figure 9A is a pictorial view of side-cutting planer head.

Figure 9B is a side elevation of the planer head of Figure 8A.

Figure 10 is an exploded view of a preferred configuration of the planer head of Figure 8A.

Figure 11 is an end view of a comer-cutting planer head.

Figure 12A is a pictorial view of a front side of a corer-cutting knife for use in end portions of the planer head of Figure 9A.

Figure 12B is a pictorial view of a back side of the knife of Figure 12A.

;0 Figure 13A is a cross-sectional schematic view of an article of lumber being cut with a comer-cutting knife having a full 1/4 round cutting edge in perfect alignment.

Figure 13B is a cross-sectional schematic view of the article of lumber of Figure 12A cut with the knife of Figure 13A in imperfect alignment.

Figure 14A is a plan view of two knives, comparing dimensions thereof for cutting an article of lumber from dry and green stock.

P IOPERS ASJn J .r.iO l')0I2P71I( Spcoc S 7 00 g -6- SFigure 14B is an end view of an article of lumber shown with finished comers produced by the two knives of Figure 14A.

r-- I Figure 14C is a plan view of a positioning of the two knives of Figure 14A for S 5 finishing the article of lumber as shown in Figure 14B.

SFigure 15A is a schematic view of the knife of Figures 12A and 12B showing geometric constructions useful for defining the configuration of the knife.

Figure 15B is a schematic view of a prior art knife corresponding to the schematic view of Figure Figure 16A is a pictorial view of the knife shown in Figures 12A and 12B showing line segments used to describe the shape of a beveled surface of the knife.

Figure 16B is a partially cut-away cross-sectional view of the knife of Figure 16A taken along a line 16B-16B thereof.

Figure 16C is a partially cut-away cross-sectional view of the knife of Figure 16A taken along a line 16C-16C thereof.

Figure 16D is a partially cut-away cross-sectional view of the knife of Figure 16A taken along a line 16D-16D thereof.

Figure 17A is a schematic view of a face-cutting knife cutting an article of lumber showing an attack relief angle according to the prior art.

Figure 17B is a schematic view of a comer-cutting knife shown relative to the article of lumber of Figure 17A.

Figures IA and 1B show two orthographic views (side and top, respectively) of a high speed planing apparatus 10. The apparatus 10 has a table 12 for supporting an article of wood 14 that travels horizontally on the table. At least four planer heads 16 are provided: one (16a) above the article of wood (hereinafter one (16b) below the P MOPERSAS'Jn.;iin 6'7910 Spc; O, S/'02121' -7article of wood (hereinafter "bottom"), one (16c) to one side of the article of wood and one (16d) to the other side of the article of wood (hereinafter "side"). Each planer head rotates about a respective axis of rotation and As a result of this rotation, N in conjunction with travel of the wood 14 relative to the planer heads, each planer head cuts a corresponding surface on the article of wood, so that a top surface, a bottom surface, and two opposing side surfaces are cut. An object of this process is to produce a surface S having a high surface quality; however, it is not essential that the planing apparatus be used to produce a finished surface.

Figure 2 shows an end view of one (17a) of the planer heads 16. The head 17a has an axis of rotation A hub 18 of the head 17a carries a plurality of circumferentially spaced apart knives 20 and associated gibs 22 in corresponding pockets 19 of the hub.

Figure 3 shows one of the pockets 19a in more detail. A knife 20a and its associated gib 22a are disposed in the pocket 19a. A screw 24 is threadably received through a hole in the hub 18 and a terminating end 24a thereof extends outside the hub and bears acaimst th,, 2?a"L \kIch 20 Tu;n Ser Lars 1!c 111e 202! VsC Ii~~ force cla'mps t he kaI fe aca"ins! a s;p_ rna aLlIasoth oet aAvnamr circumrerntial spacing is -cequirud ot \'een ad1Cacent kr\ es to po vice space, for0 IDaccessing and removing, the,, screw 24., in ?hedc io of thearo A Figure 4a is a pictoria] viewv ofan alter-native pr-:or a-rt plancr he2ad l7b. shiowine.

knife 20b removed thierefrom The- kn:-ife 2GOb is clamped in a 9acke 1,b h head I T bvan ax~a!lv directed scr.-w 24, extending through an, Lupper co'Lar 2 5a and into a cor-resPonding lower Collar 25b. Referring addition to Figu re 413. the collars 25f include correspondingI ramnped p'anar portions 25ap (not visi"Hlin: IF, gure 4A) and 2Snfor ~0mating2 with coresponding ramped planar por-tions 122b-uppei anld 22b-iowver of a gib po-r-t ionr 22b of !he kn~fc 2G)nb thatl functions analogously to the gi.b 22a of the k'nife Rather than hearing agaist the knif, a-s does the gib 22a, the, Lib p.ortion 221 is ntegralv a?:ached to the knife and supports the knife, \vh~ch is canitile\:ered tlherefrom.Terfe the, gib Portion 22-b m-rust be particularly larae and robust to w:thsta-nd the requ-.ired forces, as com-Ipared to the ,-ib 22a One of the colliaS (25a) is adapted to receive the he!ad of the screw 242 and tl~e other collar- (25h) Includes thicads "Th' adapted to rec\cive th threads of- tescre.'; Inse.inig the screw through the Collar and tighte-ning the screwk :nto thei collar torces the Collars togt vcr edgi ng the collars against the -amped planar po!-rtis of the km fe and thereby forctnc the 'k-niFe apainst a back surface I Gb, of the pocket I 9b, to Clamp ,he knife to the planer head. This -onstruction provides an advantagte over theplaner head I a clescribed inmediately above in providimg the c-apbility to mov e the r !F S, f, iur. Spt ac SA 1 00 a -9knives closer to one another and therefore achieve denser knife spacing. However, this density is limited by the dimensions of the collars and the gib portions 22b, all of which IND must be robustly sized in order to withstand the required forces.

Turning to Figure 5, an end view of a face-cutting planer head 26 is shown. A hub 28 of the head 26 carries a plurality of circumferentially spaced apart knives 30. Each knife is disposed in an associated pocket 31 and has an associated gib 32. As best seen in Figure 6, showing a portion of the periphery of the hub 28 in greater detail, a screw 34 has a threaded portion for threading into a hole 35 in the hub. The threaded portion terminates in a terminating end 34a that is, preferably, contained within the hub and, in any event, is not used to exert a force on either the gib or the knife. Rather, the screw 34 has a ramping shoulder portion 34b which preferably is of frustoconical shape. The ramping portion 34b exerts increasing wedging force (in the direction indicated by the arrow against the gib 32 as the screw is tightened, the gib in turn transmitting this wedging force against the knife, to clamp the knife in place against a supporting wall 31c of the pocket 31, and against the gib, to force the gib against a front side 40 of the knife and a bottom 31b of the pocket 31. The screw 34 is shown with a male tightening member 34c; however, a female tightening member may also be used. Moreover, a female tightening member has been determined not to become loaded with wood waste during operation and the female configuration provides for greater clearance and so may, therefore, be preferable.

An angle 0 defines the ramp angle of the ramping portion 34b of the screw 34.

This ramp angle provides a mechanical advantage in translating a tightening force applied to thread the screw into the hole 35 into a clamping force bearing against the gib and, in turn, the knife. A small ramp angle q5 increases the advantage; however, if the ramp angle P %OPERS*SJi.Un Cl:'I 9Ip Spc- .du c- 00 Sis too small, too little range of movement of the gib will be provided to accommodate manufacturing tolerances between the screw, gib and knife, along with the additional Selastic compression of the parts necessary to exert the required clamping force. It has been C found that the ramp angle 0 is preferably in the range of about 10-25 degrees.

0, The combination of the screw 34 and gib 32 clamp each knife 30 in the planer head 26. The gib 32 need be no more robust than the gib 22a described above in connection with the head 17a. The screw 34 in essentially incorporating the function of the collars 25 of the head 17b can be of smaller overall dimensions than the corresponding screw and collar combination, and the gib 32 need not be as strong and therefore may be smaller and, particularly, thinner than the corresponding gib portion 22b. Thence, the screw and gib provide minimum sized components for clamping knives in a planar head, providing for maximum density of spacing of the knives and, therefore, a maximum degree or quality of surface finish.

Referring to Figure 7, the knives 30 are preferably provided with dual, opposed, cutting edges 36a and 36b and corresponding deflector ridges 38a and 38b such as described in Schmatjen, U.S. Pat. No. 5,819,826 that project from the front side 40 of the knife and extend parallel to an elongate axis of the knife. The deflector ridges define a channel 42 having a channel surface 42a. The channel 42 is effectively a recess in the front side of the knife, which may be provided in other configurations, such as a keyway. The knives 30 also have a back surface 44 that is received against the supporting wall 31c of the pocket 31.

P \3PERISASQan 1i)' .;u7 i 5pc. Sp l5.-2 2-" 00 F1-11- The recess provided by the deflector ridges 38 and the associated channel 42 advantageously define an interlocking feature adapted for interlocking with the gib 32, IN providing a double-sided, indexable knife system that securely and positively holds the Cl knife in the associated pocket. Particularly, as seen in Figure 6, for use with the preferred knife 30, the gib is adapted so that one of the deflector ridges 38a is disposed outside a toe 39 of the gib at one end of the toe, the other end of the toe being defined by a recess 41 shaped to receive the other deflector ridge 38b. The channel 42 as bounded by the deflector ridges defines a recess that, along with the relatively projecting toe of the gib 32, provide interlocking means which cooperate to index and further securely hold the knife 30 in position against the gib 32.

Referring back to Figure 7, the knife 30 has an elongate axis and, a line perpendicular to the elongate axis and passing through the cutting edges 36 of the knife defines a transverse axis "TA" of the knife. Now referring back to Figure 5, the gib 32 associated with the pocket wall 31c defines an orientation of the axis "TA" for the knife as installed in the hub 28. This orientation can be specified as an angle 01 relative to a radial line "RL" extending through the axis of rotation of the head. The angle 01 establishes the axis The angle 0 is optimized to provide a desired angle of attack for the knife and is preferably in the range of 10-30 degrees.

The hole 35 for receiving the threaded portion of the screw 34 has an elongate axs -EA that makes an a 0. relattve :o he radi0 lne R The c 0; 00 O optimized to dire:: the ciamng force auainst th.e nitfe The ainyle"' s prefer.abrange of 10 20 degrees and is detenn:mned without regard :o the angle 0. I e the axes IND'E.,A and TA" rotate together as the angle 6, is var!.

CI 5 The planer head 26 provides several outstanding advantages One advantage is Othat the manner described above for clamping each knife 30 p ov;des f--or much denser spacing of the kntves as compared to the prior an The screw 34 may be accessed and rermoved from essentially a radial direction rather than a c:rcumferential direction so that the spacing between the knives need not provide space for screw access or remo\ ai as 0 was required in the pnrior art. This denser spacing of the knives, by itseif, impro\ Cs surface iinish Moreover, this :mproved surface finish can be traded off, to any extent desired, to achieve higher production throughput by :nc: casing the speed of travel of the wood bein cut The mechanical advantage provided by the scew 34 has been found to decrease the number of screws required to achieve a g:ven clamping torce. This provides for less machine downtime, since fewer screws need to be loosened or removed in order to remove a knife for repacemnent or repair This mechanical ad\antae also makes tihe screw less nrone to loosening. so that camPrig is made more secrai It is also recogn;zed by the present inventor that each of the knives 30 ma be made ve.ry thin (dimension in Figure so that, from material considerations.

IL

becomes economical to dispose of the knives rather than repa:r :hern For example, for a typical knife that is 7/8" wide (dimension in Figure 7) and arbitrarly long (e P ,OPER\S*SI)I- 0 26 1'911 Spc dot S5v22,,UJ g -13- 00 0 anywhere from 1" to a representative dimension is only 0.082". Employing disposable knives further reduces machine downtime as well as the cost of providing and Soperating machines used for knife repair. The ability to make the knives thin is due, at least C in part, to the security of the clamping force provided by the screw 34 as well as the S 5 indexing provided by the deflector ridges.

The knives 30 and the gibs 32 need not extend the entire (axial) length of the hub 28. For example, two knives 30 and/or two associated gibs 32, axially butted against one another, are preferably used in each pocket 31, each pair of a knife and associated gib extending about half the axial length of the hub. Two axially disposed knives and/or two axially disposed gibs, or more than two axially disposed knives and/or more than two axially disposed gibs may be provided in each pocket.

The just described planer head 26 corresponds to two of the four planer heads 16a- 16d of Figures IA and IB. Turning to Figure 8A, a generalized cross-section of a length of unfinished construction lumber 4 5 UF is shown. Two of the planer heads 26 are arranged in correspondence to the heads 16a and 16b of Figures 1A and IB and cut, respectively, top and bottom faces Ft and Fb of the lumber 4 5 UF. After this cutting the lumber has a finished thickness and an unfinished width "wuf." Figure 8B shows a cross-section of the article of lumber shown in Figure 7A in a finished condition 4 5 F as a result of cutting two side faces Fs, along with four respective radiused comers with planer heads corresponding to 16c and 16d of Figures 1A and I B. Accordingly, each of the side-cutting planer heads has corner-cutting adaptations for CuT119 tx'orpdiused cornetC! s" i Ti adition1 2o a adataion fo cecn aju ne 00 rutum.g jO Figure-s 9A and 9B, a sidL-utting !,,achad 4~6 s slnowni hav no th INDcorne and face-c uting adaptat ions ju-st i nd icated. Ptc uiarv th, ie si de -cutn Llaner C9 5 head 46 has a face-cuttin cener por-ion 47 and two corner-ctig end portions 49a anc 49b, on either side of" the centecr portion 47, for cutting respectivec radiused cornu r The portins may be attached to a shaft for rotating the por-tionis as is known in ,he art or may2 beC formed integrally wit h the shafti c ngto Ftgure 10, the face-cutting center portion 47 inc -udes a huh 48 carrying l0 an puraitv ofcarcurnferentiali spaced apart knivecs 50. Each k-n!,fe 50 !s disposed inain associated pocket 51 and his an associated gib 52 A screw 54 is m!radably received through the hUb 48 The smcw 54 preferably has the same eaL.e as the sciew 34 fLo! wedging against the gib 52, and in turnT- for wedging the kniHY agains; supporting wai of the pocket 51 As the center porion 47 is used to cutL a Ila: face likef the pl!aner 5 head 26 descnbed above, the center portion is preferablv provided with all of the features of the planer head 26.

With reference to Figures 10 and 1 1 each corner-mutt end porion 49 includes a hub 58 (58k. W) in Figure l 0) can-ving a plait of circumn frent~a spaced apart knives 60. Each knife 60 is dispos-d in jn associaed pocket 61 and has an assocated gih 62. A screw 64 is threadably ree ed though the hib The screw 654 preferably has a1 ramping shoulder porion 64h that is the same as or qisidar to the ramp ing shoulder porton 34b of Bhe screw 34, for- wedging against the gib 62., an-d iit. turn- for wcd gmg th!e P OPIE iSS'Jin- )t 07\ 7W'17 II0 Sp do t2.l/x:7 g 00 knife against a supporting wall 61c of the pocket 61. The screw 64 is shown with a female tightening member 64c; however, as mentioned above, either female or male tightening member may be used.

SAs best seen in Figure 9B, the comer-cutting end portions 49 (49a, 49b) are adapted to cut two of the radiused comers shown in Figure 8B. Turning to Figures 12A and 12B, showing the knife 60 in more detail, the knife has at least one corer-cutting edge "CEI" for this purpose. It is advantageous, however, to provide the knife 60 with four corner-cutting edges "CE 1

"CE

2

"CE

3 and "CE 4 so that the knife carries a multitude of replacement edges and so that a symmetry is provided in the knife so that the knife is suitable for use in either end portion 49. However, any number of corer-cutting edges (or cutting edges) may be provided. Preferably, the four corer-cutting edges are disposed with respect to one another with 90 degree rotational symmetry as shown; generally, it is preferable to provide cutting edges with 360/n degree rotational symmetry.

The knife 60 has a front side 60a (Figure 12A) and a back side 60b (Figure 12B).

Taking the end portion 49a for example and with reference to Figure 9, to expose the comer-cutting edge "CEI," the knife is indexed to the pocket 61 by seating a first outer edge "OEi" against a bottom supporting wall 61b in the hub 58a. A second outer edge

"OE

2 is index to a sidewall 53a (see also Figures 9A and 9B) of a pocket 53 in the adjacent hub 48 of the center portion 47. Similar considerations apply in mirror image for the end portion 49b.

With particular reference to Figure 12B, the cutting edge "CE" is a portion of a nCOnCavel C] rcu lar arc for cut-ing a mu raciiused) c rorc i, u olt her s bajtesco he used for forrrnina-_ comL-ers havinpg di fferenm~ ,)ALrurlui1S A fl1 90 degreC 21rC, necessary for- cuamrg a complete 1 /4 rounmd comcir "is Shov. ni supel~-rnposed onl :hec cutting edge n dotm,-d line The 90 degree arc: 7crm.inates points 1), Cl 5 (correspondi n oP)adP-(orso to PtoP Tangent lines and that art taiwent !o the end-points P, and are spaced apart 90 degrees ByV contrast, 1,he1 culttingP e C CE" is pweferabiv less tan, a full 90 degree_- '17- and terminates at end-points P, and P 2 Tangent l:res a nd LT2 that are tanocen: to the end-points P, and P, are spaced apari grcater than 90 degrees Par',!cularv respeci. c io aligniment relief areas "RA" and "RA2'' are defined between ihe re-spective tangent lines 'LTand"L T 2 n the cor-cesponding respective tan~gent lines and -LT4 These alignmennt relief areas (or "aienrni etf' are pre,,ferably form!-ed b% crnplovtng.

preferably iho ugh not necessari!lv, stmratght Oute-r permeter sectons "OP' fiankinLe. oin each side, the cuiLng(, edge An alignmeint relief alngle 0, corre-sponlding to :Hec al gnment relte area and an lt anment relifage0 conrespondtnmo tlhu alignment iclief area "P-A 2 Lire preferably equal to each other -and are preferably: a.1;ou)t dlegrees, however, the angules can vary depending, onl need according to the followinlg con1 s Id era t Ii nS.

The alignment reliefs are provided to ensu.re that the Lnlt does no! extendL4 nto space in which it is not diesired as a result of mi sail ime-;t of the km% cs Even ifthe knives are originally perfectly; aligned, such MlSislignment1 Canl su~bsequently occur, for example, as a result of the process knowvn in the art as ''joitin-.g,- which is uLsed io sharpen the kni\ cci a ldaner head With 2 sie, W eh Whe kiTivs reai cam CT apparatus. RefertnLw to FiLoures 9A and for cotext, the stonc not show~n)t copeutn dnecs of the knife 5C' of the center portion 47 and the cut ng ediges of the bmi ye of Whe end port ons 49 at the same time., and it is ht ehl'. destrabe At te smone be C 5~ aplied to th e samec thickness of metal for all cuttinr efdges, :o provtdC for even shamening I loec ifte outer peirieter sectiors of the kraves 60 extended along the lines 'LT3" and 'IT.Q" and if the knives 60 were not perfec Mvaigntd or oriented "01n respect to -,he kriives 50, pornions of the knives 60 would project !nto space adjacent to that occupied by portins of the knives 50, -doublhng-up' on tQ amrount- of m~eta 0 confrontd by the store at such locations As another considernation. the ahgnmert reliefs prevent poten:0a interference between the corner-cutting knife 60 and an adjacent face-canting knife Ain examtpe !s shown in F7iurcs i 3A and I 3B Figure 13A shows a corner ponrton (in cross-sec w't) of ain aticle of lumber 45c .A top fAce is cut with a face-curting planer head (no*- IS shown) such as the planer head 26, whtile a side face is cu; wth the facecutting ceiater por-tion 47 ofplaner head (also net shown) adapted for cor-ncr cuttin, s,,ch as tlhe planer head 46. A corner-cultng en-;portion 49 (akso no: shown) ofithe plan~r head CLarriels a1 knife 60 having a cutting edge "CE -As show'n ths cung edge -CE' is a fA!l 1/4 round and is perfectly aiigned with respect to the top fa-ce c however, thts ;s not a prnactal ciumstance Turning to igure l 3B, if the kniife 60 is misaligned by any angle 0 that is grealer than zero, the cutting edge CE "wl cut into the top Iace YF 1 regainfless of whet her the top P OfEWSI S'Jn I, S C Spc 5 1)-S ::X1)7 00 a -1 8- 0 face is cut before or after the side face If the knife is misaligned in the opposite direction, a similar interference will occur with the side face "Fs." I The knives 50 and screws 54 of the center portion 47 of the planer head 46 are C1 preferably oriented as shown in Figure 10. Referring to Figure 11, the gib 62 associated 0 5 with the pocket wall 61c defines an orientation of an axis "TAa" in the plane of the back surface 60a (Figure 12A) of the knife 60 as installed in the hub 58. This orientation can be specified as an angle 81a relative to a radial line "RLa" extending through the axis of rotation of the head. The angle 1,a establishes the axis "TAa." The angle 01' is optimized to provide a desired angle of attack for the knife and is preferably in the range of 10-30 degrees.

A hole 65 for receiving the threaded portion of the screw 34 has an elongate axis "EAa" that makes an angle 0 2a relative to the radial line "RLa." The angle 62a is optimized to direct the clamping force against the knife. The angle 02a is preferably in the range of 0degrees and is determined without regard to the angle 0a,, the axes "EAa" and rotate together as the angle 0,a is varied.

The prior art typically provided a single knife having a straight cutting edge integrally formed with one (or two) curved cutting edges, to cut both the side face Fs and one (or two) of the corers r of the article of lumber 4 5 F in Figure 8B. The novel construction provides a number of outstanding advantages over the prior art. For example, to change the radius of the finished lumber, all that is required is to change the relatively small and inexpensive corer-cutting knives 60, while in the prior art, the entire cutting surface needed to be changed.

P \OPE P S S':m Jun l' l 111 Sp-c. N 2

I

c- -19oO Moreover, the prior art planer head was adapted for a particular knife. Turning back to Figure 10, the center and end portions are preferably provided as separate units that are bolted together as shown. Although this feature is not essential and the end portions may Sbe manufactured integrally, the feature provides for changing the width of the finished 0 5 lumber simply by changing out the center portion 47, while in the prior art, the entire planer head would need to be changed.

Taking advantage of the preferred "bolt-together" construction of the planer head 46 shown in Figure 10, the planer head can be adjusted from being adapted to cut dry lumber to being adapted to cut green lumber, and the reverse, simply by changing the knives 60 and the end portions 49.

Figure 14A shows the outline of a representative knife 6 0DRY, corresponding to the configuration shown in Figure 12A, for cutting an article of lumber of nominal size from stock that has been kiln dried. The cutting edges CEDRy have respective radii RDRY. Shown in dotted line is the outline of a corresponding knife 6 0 GREEN having larger respective radii RGREEN adapted for cutting the same article of lumber from green stock.

Figure 14B shows an of a finished 2 X 4 70 DRY finished from dry stock, corresponding to the outline shown for the article 4 5 F in Figure 9B, along with the corresponding outline of a 2 X 4 7 0 GREEN finished from green stock shown in dotted line.

The widths of the two articles differ slightly, typically by the dimensions indicated, and the radii of the respective corners RDRY and RGREEN differ as shown Figure 14A.

With additional reference to Figure 10, it is recognized that to leave the outer edges OE (Figure 14A) of the knives 60 available for indexing to the center portion 47 (particularly, the sidewall 53a) as described above, the knives 60

DRY

and 60crF,,, can be shified relative to one another as shown in Figure 1 4C (compare with 0 Figure 14A). Outer edges OE of both knlies remain positioned to contact the sidewall 53a (Figure 10) of the center portion 47, so that the same center portion can be used Outer edges OEO,, and OEcRLEN are shifted relative to one another, and this shift can be 5 accommodated by modification of the end portions 49 For example, to cut 2 X 4's from dry stock, the knife 60,Y, has the position shown in Figure 14C A cutting edge CE,, merges or aligns with the face side F, of the 2 X 4 the knife 60 R is indexed to the sidewall 53a of the center portion 47 at the outer edge OEc the knife 6 0 DR is indexed to the bottom supporting wall 61b of the pocket 61 of the end portion 49 (49a in Figures 9B and 10) at the outer edge Similarly, to cut 2 X 4's from green stock, the knife 6 0 CREE las the position shown in Figure 14C. A cutting edge CEGRE merges or a2igns wih the face side F, of the 2 X 4, the knife 6 0 crEN Is indexed to the sidewall 53a at the outer edge OEc, and is indexed to the bottom supporing wall 61b at the outer edge OE(,RLE. The outer edges OEDY and OE

C

REEN are displaced an amount from one another that is equal to V 2 the difference in the widths shown in Figure 148, and the respective depths of the pockets 61 of end portions 49 corresponding to the two knives are provided accordingly.

Preferably, the pockets 61 are identical for end portions adapted for the two types of wood stock, and the depths of the pockets are adjusted simply by changing the outer diameter of the end portion (see Figure 10), though this is not essential. In any event, to change from cutting green lumber to dry lumber or the reverse, or to change the width of the article of lumber a small amount for any other reason, only the knives 60 and the P 'O'

P

RS A S J l. 07u12 'V!n Spci da-n 00 a -21- Send portions 49 need to be changed; the more expensive center portion 47 may be used for either purpose and therefore may remain in the cutting apparatus.

IN Turning to Figure 15A, the knife 60 has a distinct configuration that can be defined C with reference to lines "BL" that bisect the cutting edges CE of the knife. Each cutting edge CE is preferably semi-circular as described above and, therefore, has a radius of curvature Rc that is constant. The radii of curvature extend from respective focal points Pf that lie on the lines BL. The lines BL intersect the cutting edges at respective points PI and vectors extending along the lines BL in the direction from the points PI to the points Pf diverge from another as shown, they do not cross one another. Figure 15B provides a comparison with a prior art knife having two curvilinear cutting edges. The same principles can apply to distinguish knives 60 having more complex curvilinear shapes for the cutting edges.

Figures 16A-16C illustrate another feature of the knife 60. As seen in Figure 16A, a number of line segments "LS" are shown on a beveled face "Fb" that includes the cutting edge CE 4 shown in Figure 12B. The line segments "LS" are lines perpendicular to both an outer peripheral contour "OCa" that defines a periphery of the front surface 60a of the knife (not visible in Figure 16A-see Figure 12A) that includes the cutting edge "CE 4 and a corresponding, parallel outer peripheral contour "OCb" that defines a periphery of the back surface 60b of the knife. The line segments "LS" are therefore of minimum length for connecting the two outer contours. As the line segments "LS" are geometric constructions rather than distinct physical features, there are an infinite number of the line segments "LS" defining the beveled face "Fb." P OPE r i 7N l U Sp- ac. Ix)7 S-22 00 O Figures 16B-16D are cross-sections of the knife 60. Each cross-section is taken in a t plane perpendicular to the front surface 60a, the parallel back surface 60b, and (c) IN the respective outer contours "OCa" and "OCb," and includes one of the line segments CN Particularly, Figure 16B illustrates the cross-section indicated in Figure 16A that 0 0 5 includes the line segment "LS5se," Figure 16C illustrates the cross-section indicated in Figure 16A that includes the line segment "LS 5 sc," and Figure 16D illustrates the crosssection indicated in Figure 16A that includes the line segment "LSisD." Each of these line segments is angled, as are all of the line segments with respect to the plane of the front side 60a of the knife, by a substantially fixed angle y that is preferably in the range of 25-40 degrees. The angle y is referred to herein as an "attack relief angle" to distinguish it from the alignment relief angle described earlier. As can be seen in Figure 16B for example, the attack relief angle y is defined between the line segments LS and the undersurface 60a (Figure 12A) of the knife.

Referring to Figure 17A, a schematic drawing of an elongate article of lumber 45 is shown being cut or chipped by a knife 75 rotating in the direction indicated and defining a cutting arc The knife 75 corresponds to the face-cutting knife 50 of the center portion 47 of the planer head 46 shown in Figure 10. The article 45 extends along an elongate axis "EALUMBER." An angle Al. with respect to the elongate axis having some nonzero magnitude must be provided to avoid hammering the wood with an undersurface "US" (or 60a in Figure 12A) of the knife 75. Such hammering deleteriously affects the surface finish provided by the knife.

Figure 17B views the article of wood shown in Figure 17A from a direction perpendicular to the axis "EALUMBER." The knife 75 is omitted, but a corer-cutting knife P IOPER S A S\rJl lr, Q SpIlk Ia 20:/U17 00 a -23-

O

O 77 according to the present invention is shown. The knife 77 has a front side 60a and two outer contours OCa and OCb as described above. The line segment "LSL" in Figure 17B IN corresponds to the line segment "LSi6B" in Figure 16B and, therefore, provides an attack CI relief angle y as shown in Figure 16B. Thence, line segments LS are provided by the knife l"- S 5 77 in the longitudinal direction, the direction of EALUMBER." An outstanding advantage of the knife 77 is that the knife 77 also provides line segments LS orientated in the transverse direction "TLUMBER." Particularly, the line segment "LST" shown in Figure 17B corresponds to the line segment "LSI 6 D" in Figure 16D and, therefore, provides an attack relief angle y as shown in Figure 16D. Moreover, the knife 77 provides an attack relief angle of y in every and all intermediate directions.

The invention the attack relief angle is constant over the surface "Fb" (Figure 16A) as mentioned above; however, this is not essential.

The curvilinear knife 77 is provided independent of the corresponding face-cutting, linear knife and it is therefore relatively easy to provide an optimally configured surface Fb. For example, it is relatively easy to manufacture the knife 77 with a constant attack angle of relief over the entire surface Fb. Moreover, because the curvilinear knives are staggered with respect to the corresponding 0 n face-cutting knives so that their cutting surfaces overlap, jointing the knives does not increase the width of the cut or cause surface imperfections such as lines at the apparent r points ofjoinder of the respective cutting surfaces.

\O

N It is to be recognized that, while a particular high speed planer head has been shown and described as prefened, other configurations and methods could be utilized, in addition to those already mentioned, without departing from the principles of the invention.

The terms and expressions which have been employed in the foregoing specification are used therein as terms of descnption and not of limitation, and there is no intention in the use of such terms and expressions to exclude equivalents of the features shown and described or porions thereof, t being recognized that the scope of th invention is defined and limited only by the claims which follow.

The disclosure of the complete specification of the parent application as originally filed is incorporated herein by reference.

Claims (16)

1. 2. The knife of claim 1, wherein said cutting edges are concave and semi- circular.
2. 3. The knife of claim 2, where 4.
3. 4. The knife of claim 3 including, associated with at least one of said cutting edges, substantially linear outer perimeter portions that provide respective alignment reliefs with respect to lines tangent to the ends of said at least one of said cutting edges. The knife of claim 4, wherein said reliefs define alignment angles of relief between said lines and said outer perimeter portions that are at least about 20 degrees. P \OPER\SSUQn-Juw )7i2 b'9 10 Ct,. am 2-7 S1 -26- 00
4. 6. The knife of claim 1 including, associated with at least one of said cutting IN edges, substantially linear outer perimeter portions that provide respective alignment C, reliefs with respect to lines tangent to the ends of said at least one of said cutting edges. S
5. 7. The knife of claim 6, wherein said reliefs define alignment angles of relief between said lines and said outer perimeter portions that are at least about 20 degrees.
6. 8. A wood-cutting knife comprising at least two spaced apart, concavely curvilinear cutting edges, wherein respective lines bisecting said cutting edges extending from respective points of intersection therewith to respective centers of curvature thereof diverge from one another, the knife having a planar front side, a spaced apart, planer back side and a beveled face connecting said front and back sides at respective outer peripheral contours thereof, wherein the outer peripheral contour of said front side includes one of said cutting edges, wherein, in a cross-section of the knife taken in a plane perpendicular to the plane of said front side and to the peripheral outer contour thereof, said beveled face defines an attack relief angle with respect to said plane, wherein said attack relief angle is in the range of 25-40 degrees.
7. 9. The knife of claim 8, wherein said cutting edges are semi-circular. The knife of claim 8 or claim 9, wherein said attack relief angle is constant over said beveled face. P 'OPEV RSAS\Ju.-J. 07: 6''7119 1 C-m dc ,!7 -27-
8. 11. The knife of claim 10 including, associated with at least one of said cutting edges, substantially linear outer perimeter portions that provide respective alignment reliefs with respect to lines tangent to the ends of said at least one of said cutting edges.
9. 12. The knife of claim 11, wherein said reliefs define alignment angles of relief between said lines and said outer perimeter portions that are at least about 20 degrees.
10. 13. cutting edges. The knife of claim 12 having four spaced apart, concave semi-circular
11. 14. The knife of claim 13, wherein said cutting edges are spaced apart from one another with 90 degree rotational symmetry.
12. 15. The knife of claim 8 including, associated with at least one of said cutting edges, substantially linear outer perimeter portions that provide respective alignment reliefs with respect to lines tangent to the ends of said at least one of said cutting edges.
13. 16. The knife of claim 15, wherein said reliefs define alignment angles of relief between said lines and said outer perimeter portions that are at least about 20 degrees.
14. 17. cutting edges. The knife of claim 16, having four spaced apart, concave semi-circular P OPEkUS SU 7 Ju C012t ,l1 ,Clm doc.22.1«] -28-
15. 18. The knife of claim 17, wherein said cutting edges are spaced apart from one another with 90 degree rotational symmetry.
16. 19. A wood-cutting knife substantially as hereinbefore described with reference to Figures 5 to 16D and 17B of the drawings. IND O 8 5 t'l