CA2215915A1 - Methods and apparatus for orienting power saws in a sawing system - Google Patents

Abstract

A computer-controlled sawing system (10) having a suspension beam (30) and linear bearings (110, 112) for supporting a respective power saw (26), and an angular positioner (86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106) for angularly rotating the power saw about an axis (86) offset from the rotating axis of the saw blades, a pair of material conveyors (32, 44) angled upwardly toward the back of the sawing system to provide easy loading of material thereon. A front portion of each material conveyor includes an enclosed takeup mechanism (184) that is compact and allows the material conveyors to be placed close together for cutting short lengths of boards.

Description

WO 96J~9~84 PCT/US96/~)3878 METHODS AND APPARATUS FOR ORIENTING
POWER SAWS IN A SAW~G SYSTEM

S Cn)ss Reference to Related Applications This application is a continuation-in-pzrt of Application Serial No. 08/588,741 filed January 19, 1996, entitled "MElllODS AND APPARATUS FOR ORIENTING POWER
SAWS IN A SAWlNG SYSTEM," which is a conlinualion-in-part of Application Serial No.
08/408,539, filed March 22, 1995, entitled "METHODS AND APPARATUS F~R ORIENT-10 ING POWER SAWS ~ A SAV~G SYSTEM."

Reference to a Miclofiche Appendix A microfiche appendix having one page of microfiche with a total of 48 frames of a computer program con~titutes part of this specification.

Te-' --' Field of the I~
The present invention relates in general to auk~ d sawing systems, and more particularly to techniques for orienting a number of power saws through which wood stock is moved to cut various angles therein.

-I -CA 022l~9l~ lss7-os-ls wo 96/29184 PCT/US96tO3878 Backg~und of the L.~
o,..~ed sawing m~chinPs and systems are well known and readily available for a host of ~iirL.~,..L applications. For example, there are many types of computer-controlled sawing systems to which lumber is fed so that it is cut in prescribed lengths and at various S angles, according to a cut list entered into the co."~ . In many prefabricated wood structures, various co,..pollc..L~ thereof are cut and pre-assembled, using automated sawing m~nhinP,s to cut the lumber to various lengths and at various angles at the ends of the pieces.
As one example, the web and chord co---pol1c.-l~ of wooden trusses are often cut and pre-assembled at a factory and then llan~G~led to the construction site of rebuilding floors, roof 10 structures, and the like.
Automated sawing systems for cutting the outer chord pieces and the inner web pieces of trusses are highly developed and automated to provide accurate, high speed cutting operations. One such cutting system is known as the "Aulo..la~l~,." saw, model 341, obtain-able from Alpine F.n~ineered Products, Inc., Grand Prairie, Texas. In such type of saw, the 15 system is COIIIIJ~ I controlled to move a number of individual saws and simultaneously cut both ends of a board to desired angles in a single pass through the system. A board is m~nn~lly loaded on a frontal chain-type material conveyor which transports the board to the cutting area of the system. The board is fed by the material conveyor between a pair of left-hand mounted saws and a pair of right-hand mounted saws, so that the ends of the board can 20 be cut subst~nti~lly simnlt~neously. The right-hand set of saws are mounted on a track and can be moved to accommodate different lengths of boards. Further, each of the individual saws can be moved at dirr~.~... angular o.;e.~laLions with respect to the material conveyor so as to saw each end of the board at desired angles as the board moves through the sawing system.
In such type of system, each circular saw blade is mounted directly to an electric 25 motor, and the motor is rigidly fixed to the planar face of a large gear-driven sprocket wheel.

CA 0221~91~ 1997-09-19 WO 96129184 PCI~/US961~3878 The lar~e sprocket wheel is not circular, but is C-shaped with a portion of the middle removed so that the end of a board to be cut can be moved through the saw blade without i,.l~.r~ .~ ..ce by the sprocket wheel. The inside curved surface of the C-shaped wheel is bearinged so that the wheel and the power saw mounted thereto can be rotated about an axis that passes parallel 5 to the fiont face of the saw blade. In this manner, the saw can be angled to di~.~..l positions and be able to cut through a single point on the board without any cGl~ e ho,i~oll~l movements of the saw. I~..po~ ly, the axis of pivotal movement of the saw does not contain a shaft or other appa,al~ls, but rather is in the center of the C-shaped sprocket wheel which is void of apl.a.alus, except for the saw blade, so that a board can be freely carried through the 10 saw path.
The angle of the saw blade can be oriented to di~.e.-l positions by turning the sprocke1 wheel with a gear-driven ~-,cchani~.... The large sprocket wheel is mountPd for rotation with respect to a complicated bearing arrangement that l~i~Llh~iS l~lb,icalion frequently to prevent galling or wear to the curved bearing surfaces. Any wear in the gear or bearing 15 surfaces leads to inaccuracy in the precise angular positioning of the saw blade, as well as slight play or wobble of the saw blade during actual sawing. Further, the entire C-shaped sprocket wheel and saw motor can be moved vertically by way of an electric screw-driven arrangennent. In like manner, the entire set of right-hand mounted saws can be moved ho~;~o~ lly by a gear driven assembly. Only the right-hand set of power saws needs to be 20 moved h~r;,olllally, toward or away from the left-hand set of power saws to accommodate dirr~.~..l Iengths of boards.
With regard to the sprocket wheel arrangement for angling each saw blade, the motor and saw blade are fixed to the sprocket wheel such that when moved through an arc of angles, an axis of pivotal movement is parallel to and extends through the plane of the front face of 25 the saw blade. In this manner, to change the saw cut from a thirty degree angle to a forty-five CA 0221~91~ 1ss7-os-1s Wo 96/29184 Pcrluss6lo3878 degree angle, only the sprocket wheel and ~ ch~d saw require angular movement, without a corresponding vertical adjustment of the le~yc~ e electric screw-mech~ni~mc As further noted in conne~;lion with the Aul~,l,lasl~l saw system identified above, the in-feed chain conveyor is constructed such that an operator places a board on an upwardly-5 angled portion of the conveyor where such board is carried to a knee point, at which point theconveyor is oriented ho,;Gonlally to carry the board laterally into the sawing system. A chain-driven hold-down assembly holds the board to the material conveyor during ho,;~on~l movement of the board into the sawing system. With this type of structure, while it is convenient for the operator to load the lumber on the conveyor without having to lift it 10 shoulder high, when the board is carried over the transition knee point to the hGIi~olll~l part of the conveyor, the board often tumbles or is rolled before it is clamped and thus becomes mi~lignecl with respect to the left-hand set of saws and the right-hand set of saws.
The in-feed chain conveyor of the AuLoln&~ ,. saw has two sets of parallel feed chains for carrying the board into the sawing system. One chain conveyor can be ho,; onlally 15 moved along the frame with the one set of power saws, toward or away from the other set of power saws, to accommodate di~.e.,l lengths of boards. In order to accol"",odate short boards, i.e., about two feet and shorter, the pair of parallel chain conveyors must be moved together, adjacent each other, so as to be able to move the short board between the left-hand set of saws and the right-hand set of saws. In practice, it has been found that because of the 20 drive bearing arr~n~emellt at the rear of the conveyors, the chain-tensioning linkage and apparatus required at the frontal part of each chain conveyor, such conveyors cannot be moved a close to each other as would be needed to cut very short pieces of wood.
As noted above, one set of power saws is movable horizontally along the frame, as is the co.l~,~onding hold-down meçh~ni~m and chain conveyor. The power drive for the hold-25 down mech~ni~m and the movable chain conveyor is a long square drive shaft that extends WO 961~'9~84 ~ PCTJUS96Jll3g7g eccçnti~lly the length of the saw system. Various apparatus is driven by the drive shaft using a square tubular mPmher through which the drive shaft extends to rotate the tubular member.
The tubular member l,a,lsr~l~ the torque to the driven appa~a~us. Because of the torque required~ to drive the appaldLus via the square drive shaft, the metal-to-metal driving engage-S ment between the square shaft and square tubular m~ causes wear, thus requiring eventualreplacernent. To replace the worn parts, the procedure is time concuminE, as much of the a~alal~ls requires dic~cc~nnbly and then corresponding assembly using new, and often .,n~ e parts.
In view of the foregoing, it can be seen that a need exists for further improvements in 10 autQm~teci sawing systems to reduce costs, m~ lc.u.uce~, increase the speed of operation, and generally provide an overall improvement with respect to ac~u~a~y and efficiency.

CA 0221~91~ 1997-09-19 Summaly of the Illvenffon The foregoing shortcomings and disadvantages are either elimin~tecl or ~ lly reduced by the use of one or more of the aspects of the present invention. In accordance with the p.~r~ d embodiment of the invention, two of the four power saws are mounted to 5 respective suspension beams by linear beal;l-gs for horizontal movement. However, all four saws can be positioned to different angular positions to cut respective angles in the truss boards. The s~cpencion beam is ofi~,.lled hol;~ol,~lly so that the power saw can be moved in fine hlcl~lllellL~ in a horizontal direction, and m~int~ined in a precise spatial position. The power saw is mounted to the ~ cl,~ n~;on beam via a rotatable shaft, and the shaft is driven by 10 a gear-reduction motor to move the power saw to various desired angles. The axis of angular movement of the saw blade need not be disposed in the plane of the saw blade, but rather can be conveniently offset from the saw blade so that when the power saw is moved in an angular direction, the saw blade is swept through an arc. By utili7ing the linear bearings and the beam for mounting the power saws, the cost of the unit is reduced, as is the m~ nce thereof 15 compared to the prior art sawing system. The gear-reduction positioning of the power saw assures precision and stable positioning thereof.
A related feature of the invention resides in the positioning of the two hol;~ol~l~lly movable power saws, based on the angular position of the associated non-horizontally movable power saw to thereby carry out precision cuts in the board at precise locations. Because the 20 power saws are no longer rotated about an axis that passes through the plane of the saw blade, whenever the angle of the blade is çh~nge.l the horizontal position is also changed to make a cut through a desired point on the board. Hence, based on the particular angular oli~;nlation to which the saw blade is positioned, the cO",p.l~. of the sawing system processes a m~them~ti-cal equation to dete~mine whether, and how much, the power saw must be horizontally moved 25 to achieve the angle cut through a predefined point on the board. Moreover, when a board CA 0221~91~ 1997-09-19 WO 961291~4 PCTJUS96Jl~3878 end is to be cut with two angles, the processing of the m~tllem~tic~l equation takes into consideration the angular position of one power saw to deterrnine the holi~unlal displacement of the other power saw to achieve both of the desired angle cuts through the predefined point on the board.
In acc~"~dancc with another feature of the invention, the in-feed chain conveyors are not constructed with a knee between an upward-angled portion and a ho.iGo,-lal portion, but rather are straight along the length thereof, and angled upwardly from a lower in-feed entry end to an upper rear portion thereof which is disposed b.,~ n the left and right power cutting blades. With this arrangement, the ope.~lur can easily load lumber thereon at the in-feed end, a short height above the floor, whereby the conveyor carries the boards upwardly and into the power saws of the cutting system.
In accordance with yet another feature of the p.~;fc.,~id embodiment of the invention, the material conveyor is constructed with two chain-feed material conveyors which have cantilevered drive bearings at the back ends thereof, and take-up mech~ni~m~ that are generally internal to the body of the conveyor, thus reducing the width of each conveyor. In this manner, the chain conveyors can be moved very close to each other, thereby allowing very short lengths of boards to be carried and cut by the power saws.
In a second embodiment of the invention, the sawing system has five power saws.
Two of the power saws are movable linearly in a ho.;Gc.lllal direction, two of the power saws are movable linearly in a vertical direction, and one is movable linearly in both a ho.;Gc,lllal and a vertical direction. The saws are controllable by a computer having an çx~cut~kle program. The program orients the saws to make cuts at different angular positions and linear .li~t~nceS.
In another aspect of the invention, a lift assembly is secured to the power saw for 25 moving the power saw in a sub~ ly vertical direction. A lift drive is operable connected CA 0221~91~ l997-os-ls wo 96/29184 PCT/US96/03878 to the lift assembly. The lift drive is electrically connected to the COIllp~ ,. SO that the vertical position of the saw can be adjusted by the computer.
In another aspect of the invention, a method positions the saws such that tips of the saw blades barely extend past an upper edge of a workpiece. The hold-downs are positioned 5 near the tip.
In yet another aspect of the invention, the method parks the power saws not ac-cign~d to make a cut. Parking sets the power saw completely above or outside the board to be p.~,cessed.

CA 0221~91~ 1997-09-19 WO 961?9~8,4 PCT/US96/03878 Bnef D_ nr~in of the Dlawing Further features and advantages will become more ap~a-~i"l from the following and more particular desc.i~lion of the p-~;fe..~d and other embodiments of the invention, as illustrated in the acco.."~)al.ying drawings in which like lcr~ ,nce characters generally refer to 5 the same parts or elements throughout the views, and in which:
FIG. I is a generalized view of the a~&l~ s of the cutting system employing the various Eeatures of the invention;
FIG. 2 are views of a wooden web for a truss, as the wood stock progresses through the sawing system of the invention;
FIGS. 3a and 3b are views of the a~)a,~lus for movably mounting a power saw to the sawing system;
FIG. 4 illu~lrdlt;s the various angles at which the power saw can be ol;ellted according to the mounting a~a~aLIls shown in FIG. 3;
FIGS. 5 and 6 are r~ccli~e side and end views of the sl-~pen~ion beam of FIG. 3;
FIGS. 7a-7d illustrate the relationship between the angles to be cut in a truss board, and the calculation of a correction factor by which a horizontal movable power saw of the sawing system must be displaced to make an angle cut through a predefined point on the board;
FIGS. 8a and 8b are flow charts showing the basic steps carried out by the sawing 20 system CollllJul~ l to position the four power saws according to the calculation of the correction factors and angular position data;
FIG. 9 is an exploded view of the drive mechanism of an upper portion of the material conveyor of the invention;
FIG. 10 is a cross-sectional view of a material conveyor drive assembly with replace-25 able plastic inserts between the driven metal parts;

CA 0221~91~ lss7-os-ls wo 96/29184 PCT/US96/03878 FIG. 11 is a back view of the top portion of the material conveyor of FIG. 9;
FIG. 12 is an exploded view of the chain take-up mechanism of a bottom portion of the material conveyor of the invention; and FIG. 13 is an isometric view of the assembled portion of the material conveyor of FIG.
5 12;
FIG. 14 is a generalized view of a second embodiment of the sawing system;
FIG. 15 is a perspective view of a power saw mounted to a lift assembly and a support beam;
FIG. 16 is a top view of the power saw mounted to the lift assembly and the support 10 beam;
FIG. 17 is a partial cross-sectional view of the power saw mounted to the lift assembly and the support beam taken along line 17-17 of FIG. 16;
FIG. 18 is a p..:.~,e~ e view of a power saw mounted to a lift assembly;
FIG. 19 is a top view of the power saw mounted to the lift assembly;
FIG. 20 is a schematic view of the "home" placement of the power saws in the second embodiment of the sawing system;
FIGS. 21a and 21b are front views of a truss having a truss board having a scissor cut;
FIG. 22 is a flow chart showing the basic steps carried out by the sawing system computer to position the power saws acco,Jh~g to the calculation of the linear offsets and 20 angles;
FIGS. 23a and 23b illustrate the relationship of saws 40 and 500 with respect to the angles to be cut in a truss board, the linear offset calculations, and the minim~l exposure of the saw blade tip of saw 500;

W<~ 9612g~4 PCTllJS96J03X78 FIGS. 24a, 24b, and 24c illustrate the relationship of saws 40 and 500 with respect to the angle:s to be cut in a truss board, the linear of~set c~lc~ tion~ and the minlm~l exposure of the saw blade tip of saw 500; and FIG. 25 illu~l~aLes the ~ f~nce for carriage length b~L~II carriage 20 and movable 5 carriage 22.

CA 0221~91~ lss7-os-ls Wo 96/29184 PCT/US96/03878 Detailed D~ .Lon of the 11.~ -n A sawing system 10 employing the features and advantages of the present invention is shown in generalized form in FIG. 1. The sawing system 10 of FIG. 1 can be located in an assembly operation where lumber or boards are input on a sepalale conveyor system (not S shown) and carried to the sawing system 10. The opc.aLur can then m~ml~lly move the lumber from the conveyor to the sawing system 10 for cutting to the a~lulu.iale lengths and angles. Then, the cut lumber is m~nn~lly removed, or carried on another conveyor (not shown) to an assembly table where the cut lumber is laid together and factençd by nails or other hardware.
The sawing system 10 includes a frame structure 12 to which the other components are fixed so as to m~int~in the system in a unitary manner so that it can be lld~ olled or otherwise shipped or operated as a unit. The frame structure includes an upper back frame member 14, and a lower front frame member 16. The sawing system is collllu~ d~ and thus includes a cabinet 13 to house the computer and the associated electrical circuits and control equipment. The cabinet 13 may include a CRT 15, and various manual controls 18, such as knobs or push buttons for allowing the ope.dlor to communicate with the computer, in le,l ollse to prompts and information displayed on the CRT 15. Those skilled in the art can readily devise of the electrical hardware and software for controlling the sawing system 10 in the manner described below.
In accordance with the plefe.l~d form of the invention, the system frame structure 12 Joll~ a fixed power saw carriage assembly 20 and a movable power saw carriage assembly 22. The fixed power saw assembly 20 includes a rldllle~ork 24 that supports two power saws 26 and 28 mounted at the right of the system frame structure 12. The right hand set of saws can be independently angularly positioned with a high degree of precision and stability for cutting lumber at various angles. The f~dl~c~vulk 24 is welded or otherwise f~ctened to the CA 0221~91~ 1997-09-19 W~:3 96129'L84 PCT/US96~03878 system frame structure 12. Further, the right front power saw 26 is movable about twenty-one inches ho,;~onlally on a r~,s~,ccti~e sl-~p~n~ion beam, which is shown as ler~.~ncc numeral 30.
The other associated right back power saw 28 is not longitl~lin~lly movable, but is fixed with respect to such movement. The angular movements of both power saws 26 and 28, as well as S the longit~ in~l movement of power saw 26 via the ~ ion beam 30, can be controlled autom~tic~lly by a computer control mounted in cabinet 13, or m~nl-~lly by way of the cu",~.lL~, and controls 18. Conventional DC drive controls are utilized by the CGIllp~lL~,l to drive the motors that provide angular displ~ce~ of all four power saws, as well as to provide ho,.Gonl~l displacements of power saws 26 and 40. With such type of drive controls, 10 the amplitude of the DC voltage determin~s the speed of the motor, while the duration of the voltage controls the time by which the motor is active.
The fixed power saw carriage assembly 20 also includes a material conveyor 32 angled downwardly to a frontal portion thereof to facilitate loading of boards or lumber thereon. A
hold-down mechanism 34 disposed above the material conveyor 32 functions to hold lumber 15 down on the material conveyor 32 to prevent tumbling or unwanted movement of the lumber.
As will be described in more detail below, the material conveyor 32 is driven by a square shaft 36 which is itself driven at one end thereof (not shown).
The movable power saw carriage assembly 22 includes eS~enti~lly the same compo-nents as ~he fixed power saw assembly 20, but is longitn~iin~lly movable up and down the 20 system frame 12. To that end, the movable power saw assembly 22 includes first and second associated power saws 38 and 40, where power saw 40 is suspended from lej~,e-;Li~e movable suspension beam 41. While the left back power saw 40 can be moved both ho,i~o~lL~lly and angularly, the left front saw 38 can only be moved by angular rotational movements. Both power saws 38 and 40 are controlled so as to be positioned at desired angles for cutting boards 25 at co"~i".onding angles. The power saw ~ .e~lcion assembly of power saw 40 is connected CA 0221~91~ 1997-09-l9 to a movable carriage framework 42 which, in turn, rests on the system frame 12 via rollers 43. Conventional roller assemblies are utilized for providing movable ~ h...~ above and on each side of a rail which is attached to the horizontal frame members 14 and 16. The movable framework 42 and rollers 43 allow the carriage 22 to be moved lon~ in~lly on the frame 12. Further, the carriage framework 42 is driven by a rack and spur gear arrangement (not shown) so that the movable power saws 38 and 40 can be positioned very accu~lely along the system frame 12 with respect to the fixed power saws 26 and 28, thereby enabling the cutting of angles at each end of a board, and leaving the board with a precise overall length. The movable power saw assembly 22 further includes a material conveyor 44 which, together with the acsoci~ted material conveyor 32, forms an in-feed or entry point of a material conveyor 46. A hold-down mech~nicm 48 is ~iicposed above the material conveyor 44, and is operable to move downwardly to clamp a wc.r~iccc- to the material conveyor 44, and thus move the workpiece into the sawing system. An electrical umbilical chord (not shown) having a cable carrying all the electrical power and control signals is connected to the movable power assembly 22 and travels with the assembly as it is caused to move up and down the system frame 12, under control of the computerized control in cabinet 13. It should be noted that the power saws 38 and 40 are independently powered by lcis~,cclive motors, as are the power saws 26 and 28 associated with the fixed carriage 20. However, the material conveyors 32 and 44 are each powered from the common square drive shaft 36. The pair of hold-down mech~nicmc 34 and 48 are driven by the same source as the square drive shaft 36 to move ~ c~,live hold-down chains.
It can be appreciated that the long pieces of lumber, the movable power saw assembly 22 is moved to the left in FIG. 1, carrying with it the movable material conveyor 44 and associated hold-down mech~nicm 48. In order to cut very short pieces of lumber, the movable power saw assembly 22 is moved to the right, very close to the fixed power saw assembly 20.

CA 022l~9l~ lss7-os-ls WO 96~29184 PC~rluS96JO3878 The material conveyor 32 and the hold-down mechanism 34 associated with the fixed power saw assembly 20 are movable longitudin~lly a short ~~ict~nce by a rack and spur gear arrangement (not shown), in coordination with the longitu-lin~l movement of the s~ ne;on beam 30. With such a coordinated movement of the appalalus, the power saws 26 and 28 5 cannot ~e moved into the associated material conveyor and cut into the metal thereof. The left-hand material conveyor 44 and the associated hold-down mech~nicm 48 function in the same manner with respect to the movement of power saws 38 and 40.
FIG. 2 illustrates the various stages of a board as it is processed through the cutting system 10. An uncut piece of lumber, such as shown by reference numeral 60, is loaded on the material conveyors 32 and 44 of the in-feed system 46. This is easily accomplished, as the frontal portion of the in-feed system 46 is at an optimal ~ t~nce above the floor, e.g., about thirty-two inches, thereby elimin~ting the need for the operator to lift boards to uncomfortable heights. As noted in FIG. 2, the uncut board 60 con~tit~tes raw material with either square or rough ends. Next, the chain (not shown) of each of the material conveyors 32 and 44 have 15 steel dogs that pull the board 60 forward until it is secured under each hold-down mechanism 34 and 48. Each hold-down mecll~nicm has a driven chain which engages the top of the board. The chains of the hold-down mechanism 34 and the associated material conveyor 32 move at the same speed, and thus uniformly move the board into the sawing system.
~ccurning the fixed power saws 26 and 28 and the movable power saws 38 and 40 are 20 to be set up to cut two angles at each end of the board so as to achieve the board shown in the top illustration of FIG. 2, the following steps are carried out. First, the sawing set up would be programmed into the computer to move the movable power saw assembly 22 toward the fixed power saw assembly 20 so that the power saws can then be angled and moved on their e~ ion beams to achieve the correct angles and the correct length of the board.
25 It is noted that, although not a nrcecc;ly, the front right saw 26 cuts the top angle while the CA 0221~91~ lss7-os-ls WO 96/29184 PCT/USg6/03878 back right saw 28 cuts the bottom angle while the back left cuts the top angle in the board 60.
While the system 10 has been described such that the front power saws 26 and 38 p~.rO.,.. the ~cclive upper and lower angle cuts, and the back saws 28 and 40 p~l~llll the le~l,ccli~e lower and upper cuts on the ends of the board, the operations can be reversed or otherwise S c~l~nged by the apl,.op.ial~ o.;c.-l~Lions of the power saws in the .~ c~ /e frames. ~nmin~
the angles at both ends of the board are to be forty-five degrees, for example, the front fixed and movable power saws 26 and 38 would be angled so that as the board 60 is moved through such saws, the angles 64 and 62 are cut as the board is moved past the blades of frontal power saws 26 and 38 in the first cutting operation. The back power saws 28 and 40 are angled in 10 the opposite directions so as to achieve the forty-five degree cuts 68 and 66 in the second cutting operation. The entire cutting operation takes only a few seconds or so to complete.
The fully cut board is thus carried by the in-feed conveyor 46 through the saws and delivered to an out-feed structure to be carried to an assembly area.
The cut or scrap ends of the board drop onto a disposal system, such as a shaker type 15 system (not shown) that is located in the lower portion of the frame, under the left and right sets of power saws. The disposal system extends the full length of the sawing system 10.
The disposal system moves the scrap from the cutting area to a scrap ~ ros~l area. Because the disposal system is located under the power saws, more space is required to accommodate such apparalus. In order to circumvent a space problem, the material conveyors 32 and 44 are 20 angled upwardly to provide sufficient space below the power saws.
FIGS. 3a and 3b illustrate the apparatus for linearly moving the power saws 26 and 40, as well as provide angular rnovements for cutting various angles in the lumber processed by the sawing system 10. The power saw 26 is mounted for precise angular movements with respect to the suspension beam 30, and the suspension beam 30 can be linearly moved back 25 and forth with respect to the board to be cut. The power saw 26 includes an electric motor 80 CA 0221~91~ 1997-09-19 WO 96129~84 PCT/IJS96~1~3878 and an 18-inch saw blade 82, or other a~ ;ate sized saw blade. The saw blade 82 rotates about the axis of the rotating shaft of the motor 80. The electric motor 80 is fixed to a metal base plate 84 that is welded, bolted or otherwise ~tt~rh.od to a bearing shaft 86 at one corner of the plate 84. The power saw 26 is angularly moved about the rotational axis of the bearing S shaft 86. The pivotal or angular movel~ s of the power saw 26 are shown in FIG. 4 in various ~,ositions.
While in the preferred embodiment of the invention, the rotatable shaft 86 is mounted near a corner of the mounting plate 84, the pivotal axis of the plate 84 can be at any other location thereon to achieve dirr~ paths of pivotal motion of the saw blade. Indeed, the saws that make the bottom cuts 62 and 68 on the board shown in FIG. 2 are mounted for pivotal mlovement as shown in FIG. 3a, while the saws that make the top angle cuts 64 and 66 are mounted for pivotal movc.~ --l near the bottom left corner of the base 84, as viewed in FIG. 3a. Those skilled in the art may prefer to mount the rotatable shaft 86 in the middle of the base plate 84, or at corners of the base plate 84 other than described above.
With ,~r~,ence to FIGS. 3-6, the shaft 86 passes through a hole in the suspension beam 30, but is fixed thereto by a pair of bearings 88 and 90. The bearings 88 and 90 are fastened to the suspension beam 30 by bolts or other suitable hardware. The shaft 86 conctihltec an output of a first worm gear reduction drive 92. As noted in FIG. 5, the gear reduction unit 92 has an input shaft 94 connccled via a coupling 96 to a second helical gear reduction assembly 98 and a reversible drive motor 100. The motor 100 and gear reduction assembly 98 are typically available as a gear motor unit. DC power is supplied to the drive motor 10() by way of the clc~il,;cal wires 102 to drive the motor in a clockwise or counter-clockwise manner. Further, a conventional shaft encoder 104 is conn~octPd to the rear shaft end of the motor 100 to provide output signals inf~ ting the angular displacement of the motor 100. The shaft encoder output is shown as the conductors identified by rci~-.,nCe CA 0221~915 Iss7-os-ls Wo 96/29184 PCT/US96/03878 numeral 106. By ascertaining the angular displacement of the motor 100 and knowing the ratio of reductions of the gear box 98 and gear reduction 92, the angular displacement of the saw blade 82 can be accurately determined and m~int~in~d. By ~ltili7ing an overall gear reduction in excess of 1000:1, very accurate and stable angular positioning of the power saws 5 can be achieved.
With .~fe.~.lcc again to FIGS. 3, 5, and 6, the ~ p.,,~cion beam 30 is suspended by way of a pair of linear bearings 110 and 112. The linear bearings are of a conventional type.
This type of bearing includes c~,.c;;,~.onding v-groove and v-tongue rail with mating surfaces, as better shown in FIG. 6. The v-groove rail is fixed to the top of the sl-cpçncion beam 30 10 by screws (not shown) that are threaded into the top edge of the suspencion beam 30. The pair of v-tongue members of the bearings 110 and 112 are conne~ ;d together by a support 114 b~ a pair of threaded stubs 116 and 118 that are fastened to the support 114, as well as f~ct~n~od to lateral bracket members 120 and 122. The bracket members 120 and 122 are rigidly facf~ned to the carriage frame 24 or 42 of the power saws. The linear bearings allow 15 the ~ ..eion beam 30 to be accurately suspended without any vertical or lateral play.
Further, two pairs of cam followers, one of which is shown as reference numeral 124, straddle the bottom edge of the sllcpencion beam 30 to limit the sideways movement of the rail, but allow longitudinal movement of the beam 30. Each cam follower 124 is factçned to a bracket which, in turn, is f~ctçned to the power saw carriage frame. Those skilled in the art may 20 prefer to locate the linear bearings at the bottom of the suspension beam 30, and the cam followers at the top.
As can be best seen in FIGS. 5 and 6, the DC drive motor 100 and the two gear reductions 92 and 98 mounted on one side of the s~cpçncion beam 30, while the saw motor 80 and mounting plate 84 are mounted to the opposite side. This arr~ngem~nt of a~ lus 25 provides a certain degree of balance to the s--cpe~cion beam 30, in that the weight of the CA 0221~91~ 1997-09-19 WO 96/29184 PCTlUS96Jû3~78 appa.dLus on one side of the sUcpçneion beam 30 tends to offset the weight of the apparatus on the other side. This balance reduces wear on the cam followers 124 as well as uneven wear on the linear bearings 110 and 112.
A DC drive motor 126 shown in FIG. 3b provides longit~ in~l drive to the suspension S beam 30l, via a rack gear 128 and a mating spur gear 130. The end of the rack gear 128 is bolted to the sUcpeneion beam 30. The motor 126 is suitable f~ctçn~d to the power saw carriage frame in a manner not shown. Further, the drive motor 126 also includes a shaft encoder to provide feedback pulses to the co~ ,u~e. system, thereby providing position illfo~ alion as to the longitl~1in~1 position of the saw blade 82 of the power saw 26. While not shown, the motor 126 may be provided with internal or external gear reduction assemblies to reduce the speed of the spur gear 130, and thus provide more accurate ion~itu~1in~1 move.,.e..l~ of the ~u~ ion beam 30. Alternative drive mech~ ...c, such as screw drives and the like can be utilized for moving the ~u~p~ nsion beam 30 by way of the linear bearings 110 and 112.
The two power saws 26 and 40 of the sawing system of FIG. 1 are mounted for both longitu-~in~l and angular mo~ ,c.ll~ in the same basic manner as shown in FIG. 3. The power saws 28 and 38 are not mounted by way of the suspension beam and linear bearing mecha-nisms, but rather are mounted to a fixed frame structure using the bearings 88 and 90 and gear reduction units to provide only angular displacements of the lci~ecli-/e saw blades. Those 20 skilled in the art may find it advantageous to equip a sawing system with fewer or more than the four power saws described above, using either the angular rotational and/or the longitudi-nal suspension beam movement app&.alus.
As notedl in FIG. 4, the pivot point of each power saw mounted according to the invention, is coaxial with the axis of the bearing shaft 86, and does not extend through the 25 planar face of the saw blade 82. ReC~ce the pivotal axis of the power saw is offset from the CA 0221~91~ lss7-os-ls Wo 96/29184 PCT/US96/03878 blade 82, the sawing path of the board is not blocked by power saw pivoting appaldlus, nor are complicated or m~ cc intensive con")on~ "~s required. However, because the pivotal axis of the power saw is offset from the plane of the saw blade 82, at least one power saw ~oc;~tPd with the fixed power saw assembly 20 and one power saw of the movable power 5 saw assembly 22 ~ Uil~S the capability of horizontal movement. As noted above, the right front power saw 26, as well as the left back power saw 40 are mounted to rei".e~ /e su~pPn~ion beams 30 and 41, thereby allowing for precise horizontal movements.
FIG. 7a illu~llaL~;s the reason why one of the power saws in each of the left and right assemblies requires the capability of ho.i~o"kll movement in order to cut an angle through a 10 board at a precise location. As noted above, the power saw 40 is located at the left back of the sawing system, and is adapted for cutting the top angle in the board 60. Assume, for example, that a 135~ angle 133 is to be cut in the board 60, through the predefined point 131.
The back left saw 40 is controlled by the computer to rotate the power saw to the correct angular orientation, as well as horizontally move the motor via the suspension beam 41 to make the 135~ cut through the predefined point 131. Then, assume next that a 150~ angle 135 is to be cut in the top of a subsequent board. If the power saw 40 were simply rotated to the 150~ location, then a cut 135 shown in FIG. 7a is made. However, the cut 135 does not pass through the predefined point 131, due primarily to the offset rotational axis of the power saw 40 with respect to the blade. A correction can be made by moving the power saw 40 to the 20 left so that the cut will proceed directly through the predefined point 131. A cut "through" a predefined point is also construed herein to mean that the cut is made just adjacent to the point.
The c~--.p~ on to achieve the correction factor for horizontally locating the saw 40 is complicated by the fact that the associated left front power saw 38 is also pivotal about an 25 offset axis, although not movable in a horizontal direction. The technique according to the CA 0221~91~ 1997-09-19 WO 96129184 PCT)US96Jl~3878 invention for deriving the correction factor and cutting a board with precise angles through a p.~iderl.led point of the board is set forth below.
With .cire.~.lcc to FIG. 7b, assume that the board 60 is to be cut with a top 135~ angle 133 through point 131, and a bottom 600 angle 137, again through the predefined point 131.
5 In the example, the pre~erlllcd point 131 is exactly midway b~ the top ofthe board 60 and the bottom of the board shown in FIG. 7b. In order to dete-mine the correction factor, various dim~oneions between the pivotal axis of the power saws and the board must be known, it be realized that the board is constrained and fixed with respect to the power saws 38 and 40 The material conveyor 44 in conjunction with the hold-down merh~niem 48 provide the 10 function ~f fixing the board laterally with respect to such power saws.
With regard to FIG. 7c, the power saw 40 is shown with respect to the board 60. The vertical distance hl between the top saw pivot point 139 and the predefined point 131 on the board 60 must be known. Another relevant dimension of the power saw 40 is Dl which is the distance between the power saw pivot point 139 and a point perpendicular to the front face or 15 kerf of the power saw blade. Further, and with reference to FIG. 7d, the vertical distance h2 between the pivot point 141 of the bottom power saw 38 and the predefined point 131 on the board 60 nnust also be known. Similarly, the ~liet~nce D2 must be deterrnined between the power saw pivot point 141 and a point perpendicular to the front face or kerf of the blade of the power saw 38. Based upon the height of the board 60 and the particular angles to be cut 20 in the board 60, the predefined point can be easily deterrnined as a function of the diet~nces h and h2 between the respective pivot points 139 and 141 of the power saws 40 and 38. Lastly, the required angular orientations of both the power saws 40 and 38 must be known, but the angle data ,can be easily obtained from the drawings or hlfo..--alion relating to the truss chords or webs to be cut. It should be noted that the power saw 40 is pro~la,..l..cd to traverse an angular dis~lac~.. e--l of between 53~166~, with zero degrees being defined when the blade is - PCT/U~9~ ~ ~3 ~7 IP~ 2 ~ 0 1 '96 hori~ontal and 90~ when the blade is vertical. On the other hand, the left front power saw 38 is programmed to rotate through an angular range of 14~-128~. It has been found that these angular (lispl~cement.s are suitable for cutting the various angles norrnally encountered in wooden trusses.
S The power saws 40 and 38 are mounted for angular movements about the lespe.~ e pivot points 139 and 141 as shown in FIGS. 7c and 7d. It is to be understood that the right front power saw 26 is mounted for pivotal movement about the shaft 86 as shown in FIG. 3. The right back power saw 28 has a pivot point below the motor ofthe power saw and to the lower left corner of the base plate, rather than the upper left corner as shown in FIG. 3 with respect to power saw 26.
It is further noted that the range of ho. ~ollLal ~liep!~c~m~ntq of the power saw 40, due to movement of the suspension beam 30, is about 21 inches. A horizontal lert;l~,nce point from which a correction factor is determined is when the suspension beam 30 can be moved three inches to the right when facing the sawing system 10, and when it can be moved 18 inches to the left. The hol~olll~l re~el~l1ce points are entirely ~b;l~y and could be established at other positions. In other words, the re~.ence point for dete,.. ~illg hol~olllal displ~c~m~nt~ or correction factors, is at a point about one-seventh ofthe total hol~ol-l~il displ~ mçnt, as measured from the right-most end position of horizontal travel. Thus, when positioning the ho..zo.llally movable power saws 26 and 40, such saws are initially positioned at a respective 20 reference point, and then displaced therefrom based upon the calculation of correction factors, according to the following correction formula:

J~ S~

9 ~ f ~ 7 8 -2~¦D22 + h22Sin( 2 2 )Sln(4g+ 22 _ Tan~l h--) Sin(180~-612 ) 2~/D2 +h2Sin(~ 90 )Sin(135~---- Tan~l D) Sin ~

_ As noted above, h, is the vertical distance between the pivot point 139 of power saw 40 and the predefined point 131 on the board, while h2 is the distance from the pivot point 141 of power saw 38 to the predefined point 131 of the board. In the equation noted above, el is the angle of the blade of power saw 40, while e2 is the angle of the blade of power saw 38, where a zero degree I t;re, e,1ce is when the saw blade is horizontal. The correction factor resulting from the r~lc~ tiQn of this equation is the rlict~nr~e from the reference point of power saw 40 by which such power saw must be horizontally moved in order to cut the angle el through the predP!fin~d point 131 on the board 60. Positive correction factors refer to displ~cçmf!nt~ toward the left end of the m~chine, while negative correction factors refer to displ~cen~ntc toward the right of the m~r.hine, when viewed from the front ofthe sawing system 10 of FIG. 1. The portion ofthe equation is the first set of brackets, before the subtraction sign, le;ples~llLs a ~limencion contributed by the power saw 38, while the portion of the equation in the last set of brackets represents a dimension contributed by the power saw 40. For sawing systems ~tili7:in~ only a single hol i o"lally and angularly movable power saw, such as saw 40, then the only portion of the equation needed is the last bracketed portion. By utilizing the correction factor of only a single power saw, it can be holi~olll,llly moved so that any angle can be cut through the same predrfined point on the board. A similar eq~l.qtion t CA 0221~91~ 1997-09-19 WO 96/2~184 PCTJUS96J03878 noted above can be utilized for detrrmining the correction factor for holi~o"~l displacements of the power saw 26 located on the right hand side of the sawing system 10.
FIGS. 8a and 8b are flow charts depicting the general steps carried out to set up the angular positions of all four power saws, as well as the horizontal position of the hu~i~u~ lly 5 movablc power saws. Based upon the drawings of all the dimensions and angles of a truss to be cut with the sawing system, a predefined point associated with one or two angles and at each end of the board can be determined. Further, the linear ~ t~nne between the predefined points can also be determined, which riict~n~e is related to the carriage movement of the movable power saw assembly 22, again with respect to an arbitrary ~e~.el1ce position. In other words, the pa~ ters ~ 1 ~3 2, hl, h2, Dl, D2 the p,edel",cd points at each end of the board, and the t1ict~nce between the predefined points is all known either from the truss drawings" tables or other calculations. Such data is entered in a predefined format in the computer so that the colllp.lL~r can decode such information and utilize it in conjunction with the equation. When such data is loaded into the computer and the particular types of trusses associated with a program is selectecl to be run, the cor"puL~l proceeds through the generalized steps sel forth in FIG. 8. Those skilled in the progr~mming art will readily recognize that the steps of the flow chart can be carried out into many di~lc.ll program languages, utili7ing the applop.iate instructions to accomplish the result noted.
According to program flow block 300, the co."~,ul~r starts processing the truss and saw cut infolmation to derive the correction factors and the other data rl~cec~,~. y to position the a~a,~lus of the sawing system 10. In program flow block 302, the angle data and dimension data are retrieved from the ~t~b~ce associated with the particular truss board to be cut.
Program flow block 304 includes those instructions for dete~mining which saws can accom-plish the: desired cuts most efficiently. For example, the front left saw 38 can make cuts at the bottom of a board at angles between 14O-90O, whereas the front right saw 26 can make cuts at CA 0221~91~ 1ss7-os-1s wo 96129~84 PCTn~S96/~3878 the top of a board at angles between 14~-90~. If a board requires the type of cuts within the ranges noted by the front saws, then the back saws 28 and 40 do not even have to be activated. In carrying out the instructions of program block 304, the co~ e~nti~lly ~çss~s the type of cuts at each end of the board, and then assigns a particular cut to each 5 power saw, recogni7ing that one or more of the four power saws may not be required. In program flow block 306, the parameters that include the angle data and ~im~ncion data are sul-~l;L..led in the equation to the right of the subtraction sign noted above, and the correction factor for the right hand fixed power saw 28 is calculated. The right hand power saw carriage assembly 20 is fixed with respect to any ho.;~Gr.~l carriage movement. In program flow ~0 block 308, angle and dimension data co~ ,onding to the left edge of the truss board is d into the equation and the correction factor for the left fixed power saw 38 is determi~ l Then, in program flow block 310, the ~liet~n~e between the pled~,l';..~d point at each end of the truss board is calculated so that it is known where the movable carriage of the left power saw assembly 22 should be positioned. In program flow block 312, the computer calculates the correction factor for the right, front movable power saw 26. The next set of instructions carried out by the computer of the sawing system 10 is shown in program flow block 314. Here, the correction factor for the left, back movable power saw 40 is calculated.
The bracketed portion of the foregoing equation to the right of the subtraction sign is processed to cleterrnine the holi~oll~l displ~cemçnt, or correction factor, from the ler~.ence position. In program flow block 316, the co,.,~ h. drives the right hand power saws 26 and 28 to the c~lc-ll~ted angular positions. As noted in program flow block 318, the power saws 38 and 40 associated with the left assembly 22 are driven to the desired angular positions.
The sll~p~on~ion beam 30 to which the right, movable power saw 26 is rotatably ~tt~che~l, is driven ho.i~o"~lly from its ,e~rencc position accordillg to the c~lc~ ted correction factor determined in program flow block 312. This is shown in program flow block 320. Then, as CA 0221~91~ lss7-os-ls noted in program flow block 322, the s-lepçneion beam 41 to which the left power saw 40 is rotatably mounted, is displaced h~ ,lally from the re~.~ncc- position according to th correction factor calculated in program flow block 314. Lastly, the movable carriage of the left power saw assembly 22 is moved accordillg to program flow block 324 either right or left S so that the correct spacing will exist between the predefined points on each end of the board after the sawing operation is complete. In other words, the cut board is then of the correct length between the plederlned points. The computer then exists the subroutine of FIG. 8b as noted in program flow block 326. It is to be noted that all movements of the saws are processor controlled and occur at su'ost~nti~lly the same time.
From the foregoing, it can be seen that the hol;~onlal displace.ll~,.. l ~eeoci~led with the correction factor is a function of the angular orientations of both of the associated saws. In practice, it has been found that with the apparatus and c.~uil....L.,I disclosed above, angles can be cut in truss boards with a precision of +.05O, and various dimensional chala.;l~,l;stics of the truss board can be cut with an accuracy of +1/32 inch.
FIGS. 9-13 illustrate the details of one material conveyor 32 of the in-feed conveyor system 46. Particularly, FIG. 9 illustrates an upper right-hand view of FIG. 1, while FIG. 13 shows a lower left-hand view of the material conveyor 32, again of FIG. 1. As noted above, the upper portion of the material conveyors 32 and 44 rest on the ho,;~olllal frame part 14 while the lower portion of the material conveyors 32 and 44 rest on the lower horizontal frame part 16. Also as noted above, the material conveyors 32 and 44 can be accurately moved laterally by a spur and rack gear arrangement (not shown). Irrespective of their lateral positions on the frame 12, the material conveyors 32 and 44 remain driven by the square drive shaft 36. The material conveyor 32 described in connection with FIGS. 9 and 10 is substan-tially identic~l to the other material conveyor 44.

CA 0221~91~ lss7-os-ls wo 9612~1~4 PCT/US96/03878 The material conveyor 32 includes an elongate tubular metal span support 140 that s~ ;Ally spans the ~ t~nre between the top back frame l..~ ...k~. 14 and the top front frame member 16 of the sawing system frame 12 shown in FIG. 1. An upper set of cam rollers 138 and a lower set of cam rollers 141 are mounted for rotation to the bottom of the span support 140. FIGS. 9 and 12 illustrate the upper set of cam rollers 138 fixed to the underside of the span support 140, and the lower set of cam rollers 141 fixed to the span support. Each set of rollers 138 and 141 are spaced apart so as to straddle a square key stock member (not shown) along the top surface of each ho~ ,~l frame part 14 and 16 of FIG. 1.
With this construction, the material conveyors 32 and 44 are supported for holi;~o movement along the frame parts 14 and 16.
A pair of upper protective enclosure plates 142 and 144 are bolted on each side of the span support 140 via the holes, such as shown by .~ifel~,.ce numerals 146 and 148. A metal chain 150 of the conventional link-type, with dog-ear extensions 151 welded to a link every 16 inches, or so, is routed and over the top surface of the span support 140 and back inside the interior of the span support 140 and back inside the interior of the span support 140, and in between the protective covers 142 and 144. To facilitate travel of the chain 150 on the span support 140, a narrow square key stock 153 is welded to the top surface thereof. The key stock 153 provides a guide on which the chain 150 can move, as well as reduce wear on the span support 140 itself. A sprocket wheel 152 is disposed between the proteclive covers 142 and 144, and provides a drive for driving the chain 150. It is noted that the chain 150 and dogs 151 engage the lumber or wood and carry the material into the sawing system 10. The return path of the chain 150 is inside the hollow span support 140.
A pair of spaced-apart cantilever bearings 154 and 156 are mounted by bolts (FIG. I 1) to a support plate 158. The support plate 158 is welded to the pl~ Live cover 142. Both beal;llg~ 154 and 156 are mounted in a cantilever manner outside and to the left (when viewed CA 0221~91~ lss7-os-ls WO 96/29184 PCT/USg6/03878 from the back of the sawing systemj of the protective cover 142, as shown in FIGS. 9 and 11.
A flanged tubular stub 160 passes through both bearings 154 and 156, and into a QD type bushing 153. Once the tubular stub 160 is situated through the bearings 154 and 156 and snugly inserted into the QD bushing 153, the bushing 153 is tightpnpd to secure the sprocket wheel 152 to the tubular stub 160. Then, the sprocket wheel 152 is laterally adjusted for alignm~ont of the chain 150 with the span support 140. Lastly, the center part of the cantilever bearings 154 and 156 are secured to the tubular stub 160 by set screws (not shown) or other suitable means. With this arrangennent the bearing 154 and 156 support the sprocket wheel 152 in a cantilever manner for rotation and for driving the chain 150. As noted, a flange 162 having a central hole 164 therein is welded or otherwise secured to the end of the tubular stub 160. A square tubular drive ll.clllber 166 about six inches long is provided, with a flange 168 and 170 fixed at each end thereof. The flange 170 is then bolted to the flange 162 of the tubular stub 160.
Four plastic inserts 172 are provided as a durable cushion between the square drive shaft 36 and the square tubular drive mPmber 166. An end cap 174 having a square hole 176 therein is fabricated for f~etening with screws or other suitable means, to the flange 168 of the square tubular drive member 166. With this arrangement, the square drive shaft 36 is passed through the end cap 174, through the square tubular drive member 166, through the round tubular stub 160 and thus exists the prote.ili~e cover 144, as shown in FIGS. 9 and 11. Once the square drive shaft 36 is routed through the square tubular drive member 166, the individual plastic cushions 172 can be m~nu~lly inserted between the four sides of the square drive shaft 36 and the four co..~ ,onding internal surfaces of the tubular drive member 166. Once the plastic cushions 172 are installed, the end cap 174 can be secured to the flange 168 to capture the insert~e 172 and m~int~in them in place. In the ~-~ir~ d embo~im~ont the drive shaft 36 is CA 0221~91~ 1997-09-19 WO 96l29 184 PCT/US96Jl~3878 1.25 inches square, and each plastic inserts about one inch wide and about six inches long, with a thickness of about 3/8 inch.
The plastic inserts 172 are fabricated of a UHMW type of plastic that is extremely durable for transferring the rotational drive torque of the square shaft 36 to the square tubular 5 drive member 166. Other types of plastic or cushion material, such as Nylatron, may be equally effective as a durable interface between the metal parts. Each plastic insert is cut from sheet material of 3/8 inch thickness, to pieces about one each by six inches. The plastic members 172 prevent direct metal-to-metal contact between the drive shaft 36 and the tubular drive m~mbçr 166, thus elimin~ting wear between the metal parts. Rather, the wear incurred is on the plastic inserts 172, which can be easily replaced by removing the end cap 174, pulling out the old inserts, and inserting new inserts, all without having to remove the drive shaft 36 from the material conveyor 32. Moreover, with the arrangement shown in FIG. 9, the material conveyor can be moved up and down the square drive shaft 36 and yet remain driven at any axial location. It should also be noted that the top portion of the material conveyor 32 15 is not otherwise fixed to the frame system shown in FIG. 1, but rather rests on the lateral frame mçmber 14 on a set of cam rollers 138 (FIG. 9), as noted above.
Lastly, the upper end of the material conveyor 32 includes an out-feed arm 178 bolted to the protective covers 142 and 148 for catching the cut boards after having been processed through 1he sawing system 10 of the invention. The arms 178 of each material conveyor 32 20 and 44 provide a catch mechanism so that the cut boards do not fall on the floor, but rather can be accumul~ted so that they can be m~n--~lly unloaded and carried or otherwise conveyed to a truss assembly area. If a conveyor is provided so that the cut boards can be automatically l,ansl.o,led to an assembly area, the out-feed arms 178 can be elimin~ted or removed.
FIG. 10 illu~llales a cross-sectional view of the square drive shaft 36 as it passes through and drives the square tubular .. - ~.. ber 166, with the plastic inserts 172 disposed CA 0221~91~ 1997-09-19 tt,~.~b~,L~ . It can be appreciated that as the square drive shaft 36 is rotationally driven, the side walls thereof exert a torque on the plastic inserts 172 which, in turn, drive the square tubular mPmbçr 166. As noted above, any wear that wear that is caused by way of this driven relationship is on the plastic inserts 172, which are easily replaceable and inexpensive.
5 The down time of the system due to leplac~ ent of the inserts 172 is small, as only the end cap 176 need be loosened and moved away from the flange 168, the worn inserts withdrawn, and new inserts inserted. While the preferred embodiment of the invention utilizes four individual inserts 172, it can be a~lecia~d that all four inserts can be connected at an elongated corner edge thereof by a living hinge, with two of the longitu~lin~l edges of the 10 inserts being disconnected, so that the unit can be wrapped around the drive shaft 36 and slid into the square tubular member 166. It can be appreciated that the down time for removal of the worn inserts and replac~.." l~L thereof with new inserts is very short and is easily accom-plished.
It should be understood that the other in-feed material conveyor 44 is constructed in a mirror image of the material conveyor 32 described above. In other words, the cantilever bearings and drive mechanism of the other material conveyor 44 are mounted on the right (as viewed from the back) of the material conveyor 44 so that the two material conveyors 32 and 44 can be moved very close together to accommodate short pieces of lumber.
With reference now to FIGS. 12 and 13, there is illustrated the in-feed assembly CO"~;Sil~g the lower or bottom portion of the material conveyor 32. The bottom portion of the span support 140 is shown, in its relationship to a left side cover 180 and a right side cover 182 that are welded or otherwise secured to the opposing sides of the span support 140.
The side covers 180 and 182 enclose a chain take-up mech~ni~m 184 that includes a toothed chain gear sprocket 186 and a yoke 188 having a threaded adjustment rod. The sprocket 186 is secured to the yoke 188 by use of a bearing 194 that is press fit into the bore 196 of the CA 0221~91~ lss7-os-ls wo 96129184 pcTnTss6/o3~78 sprocket 186. A pin 198, welded to a square head 200, passes through the sprocket bearing 194 whiich is disposed within the yoke 188. The end of the pin 198 is f~ctened to a square head 202 by using a split pin 203 that is press fit through a bore drilled through the head 202 and the end of the pin 198. The square heads 200 and 202 fit within the square slots 204, 206 S of the l~ s~e~ re side cover plates 180 and 182. It can be seen that the sprocket 186 is longit~ldin~lly constrained by movement of the pin 198, via the square members 200, 202 in the ~ e~ e slots 204 and 206 of the cover plates 180 and 182. Further, the longitu~lin~l moveme:nt or adjuetm~nt of the sprocket 186 is obtained by way of the threaded rod 208 which is welded to the yoke 188 at one end, and is threadably adjusted by a lock nut 210 with respect IO a bracket 190. The threaded rod 208 passes through a hole in the bracket 190, and the bracket 190 is welded to the internal surface of the side covers 180 and 182 during assembly thereof. An access opening 212 is formed in the right-hand cover plate 182 for making adj-letrnentc of the sprocket 186 by way of the lock nut 210. An isometric view of the completely assembled in-feed assembly is shown in FIG. 13, with the access cover 214 removed to show the adj--etment meçh~niem Further, it can be seen that the square slide m~nnber 202 can be moved longitu~lin~lly in the slot 206 to provide take-up adjustment of the sprocket 186 and thereby loosen or tighten the conveyor chain 150. It is noted that the top portion of the left and right cover plates 180 and 182 are enclosed only on the top by metal 218 for protection which prevents small objects and the like from falling into the idler chain mech~ni~m Other spacer pegs can be welded or bolted b~ el1 the protective cover plates 180 and 182 to m~int~in the plates securely spaced apart. As further noted in FIG. 13, an opening 220 exists between the span support 140 and the cover plates 180 and 182 for exit of the chain 150 so that it can ride on the top of the key stock 153 welded to the top of the span support ]140 and thereby carry boards into the sawing system.

CA 0221~91~ 1997-09-19 It is noted that the top flat surface 218 of the in-feed assembly provides a rest on which boards can be initially placed, without being moved by the chain 150. When it is desired to feed the board into the sawing system, the op~,.alor simply pushes the board from the rest 218 onto the open top of the protective covers 180 and 182, whc.el~ the board is 5 moved forwardly by the protruding dog-ears 151. The board is then captured between the material conveyor 32 and the upper hold-down mech~ni~m 34 and automatically fed to the left and right power saws by a controlled and uniform movement. The upright edge 222 of the in-feed assembly provides an edge to prevent boards from sliding off the assembly, due to its upward incline. While the right-hand in-feed system 32 has been described, it is noted that the 10 left-hand in-feed assembly 44 is idcrltic~lly constructed in a mirror image.
The advantage of the in-feed assembly shown in FIGS. 10 and 11 is that such assemblies are very narrow, whereby the left in-feed assembly 44 can be placed adjacer t to the right in-feed assembly 32 to thereby convey very short boards so that both ends thereof can be cut at desired angles by the power saws. Further, no external adjustment apparatus 15 exists for catching of the operator's clothes or that can be covered with sawdust and the like to make adjustment difficult. Boards as short as nine inches can be cut with square angled ends, due to the feature of the in-feed assemblies which can be placed close together to support the short boards as they are carried into the sawing system. This is due also in part to the utilization of the cantilever bearings located on the outside of each material conveyor at the 20 upper ends thereof, thereby allowing the conveyor assemblies to be of a very narrow width and located between opposing saws to cut short lengths of boards.

Des-~irti- of a Second Embodiment Referring to FIG. 14, a second embodiment of the invention with five power saws is shown.Movable-power-saw-carriage assembly 22 has a first power saw 500 and a second CA 0221~91~ 1997-09-19 WO 96129~84 PCT~US96~03878 power saw 40. First power saw 500 is sl~cpçnded from movable vertical support and can be moved both vertically and angularly. Second power saw 40, ~iccucced above in detail, is suspended from movable snCpçncion beam 41 and can be moved both holi~olll~lly and angularly. Fixed-power-saw-carriage assembly 20 has a third power saw 600, a fourth power saw 26 and a fifth power saw 400. Third power saw 600is suspended from a movablevertical support and can be moved both vertically and angularly. Fourth power saw 26, liiccllc$ed above in detail, is sllcp~n~ed from movable suspension beam 30. Fifth power saw 400 is vertically and hor;zoll~ally positionable.
For the second emborlimPIlt power saws 500 and 600 are movable along vertical su~oll~. For clarity, power saw 500 is ~iccllccecl in detail with the underst~n-ling that power saw 600 s~lbst~nti~lly mirrors the mechanical structure of saw 500. The mech~nical structure and operation of power saws 26 and 40 are already set out above in detail.
Referring to FIG. 18, power saw 500 is movable vertically along a vertical support 516. Saw blade 508 has a ~ mloter of about 55.88 cm (22 inches). It should be noted that dirr~le"t-sized saw-blades can be used depending upon the length of the cut desired. Saw-blade 508 is mounted to electric saw motor 510 such that the saw blade rotates about the motor axis 511. The pivot axis of the saw motor 510, as shown, is perpendicular to and ,e~l~ the motor axis 511.
Secured to the motor mount 520 is a reversible electric motor and gear box assembly 522. A shaft encoder 504 is co~ t;cl to the rear shaft end of motor assembly 522 to provide output siignals in-lic~ting the vertical displac~lle,ll of the motor assembly 522. Assembly 522 is secured to the motor mount with bolts or the like. A lift assembly 523 has a sled plate 524 with linear bearings 530 and 532 which are slidably secured to bearing rails 534. Bearing rails 534 are ~tt~ched to support 516. Linear bearing rails 534 are mounted ~ub~nl;~lly vertically to the vertical support 516 by welding, bolting or the like.

CA 0221~91~ 1997-09-l9 Sled plate 524 is slideably faeten~d to support member 516 such that sled plate 524 and the motor assembly 522 are in the same physical frame of reference. Power saw 500 is mounted to the carriage assembly 20 (see FIG. 14) with threaded studs 528 çxt~n~in~ from lift support 516 having a longitudin~l axis aligned s~ st~nti~lly vertical.
Referring to FIG. 19, a rack gear 538 is mounted to the side of the lift support 516. A
mating spur gear 540 mounted on the gear box axle 542 engages rack gear 538. When motor assembly 522 is activated, torsional force is imparted to spur gear 540, such that the power saw 500 can be selectively raised or lowered along the lift support 526 with respect to the rack gear 538. Conventional direct current ("DC") drive controls are utilized by the co",p..l~r to drive the motors that provide angular dis~lace."c;,ll~ of power saw 500, and to vertically position power saw 500. With such type of drive controls, the amplitude of the DC voltage cleterminPs the speed of the motor, while the duration of the voltage controls the time by which the motor is active. The vertical, as with the angular and horizontal, movement can be controlled autom~tic~lly by the computer control mounted in cabinet 13 or m~nn~lly by way of the computer and controls 18 shown in Figure 14. An example of a suitable computer control is a model PC-A984-145 Compact Controller available from Modicon, Inc., North Andover, MA.
Referring to FIG. 15, power saw 400 is shown. Power saw 400 is movable longitudi-nally on a horizontal suspension beam 30 with a horizontal range of about twenty-one inches, but can be h,c,~a3ed with minor modifications. Saw blade 408 has a ~ t~ of about thirty-two inches. It should be noted that dirr~ l-sized saw-blades can be used depending upon the length of the cut desired. Saw-blade 408 is mounted to electric saw motor 410 such that the saw blade rotates about the motor axis 411. The hori~u"L~I movement mçch~ni~m for power saw 400 is the same as for power saw 26, described in detail above. The pivot point of the saw motor 410, as shown, is perpendicular to and h~L~ ls with the axis 411 of motor 410.

CA 0221~91~ 1997-09-19 WO 96J2~184 PCT/US96/03878 Lateral bracket members 120 and 122 are rigidly fastened to support member 426 by welding or the like. Fxtlon-ling from a first end 418 is a motor mount 420 with a ,~ forc~ cl.
n~mh.o~ 421 (shown in FIG. 16). Secured to the motor mount 420 is a reversible electric motor a~nd gear box assembly 422. A shaft encoder 404 is connected to the rear shaft end of S motor a,ssembly 422 to provide output signals in-lic~ting the vertical displacement of the motor assembly 422. Assembly 422 is secured to the motor mount with bolts or the like. A lift assembly 423 has a sled plate 424, a first lift support member 426 and a second lift. support lllclllbel, 427. Referring briefly to FIG. 16, sled plate 424 has linear beal;,l~s 430 and 432 which a,re slidably secured to bearing rails 434. Bearing rails 434 are attached to support 416.
Linear bearing rails 434 are mounted ~ub~l ~r~ lly vertically to the vertical support 416 by welding, bolting or the like.
Sled plate 424 is slideably f~ctçned to support member 416 such that sled plate 424 and the motor assembly 422 are in the same physical frame of reference. With respect to frame 24 shown in FIG. 14, power saw 400 is mounted to the carriage assembly 20 with threaded studs 428 ext~n"ing from lift support 416 having a longit~.lin~l axis aligned substan-tially vertical. It should be noted that power saws such as fifth power saw 400 can also be mounted to movable carriage frame 22 to achieve the same effects.
A rack gear 438 is mounted to the side of the lift support 416, best shown in Figures 16 and 17. A mating spur gear 440 mounted on the gear box axle 442 engages rack gear 438.
When motor assembly 422 is activated, torsional force is imparted to spur gear 440, such that the power saw 400 can be selectively raised or lowered along the lift support 426 with respect to the rack gear 438. Conventional direct current ("DC") drive controls are utilized by the collll)ul~l to drive the motors that provide angular displ~e~ontc of power saw 400, and to provide ho~ ,nlal displacements and vertically position power saw 400. With such type of 2~ drive controls, the amplitude of the DC voltage determines the speed of the motor, while the CA 0221~91~ 1997-09-l9 duration of the voltage controls the time by which the motor is active. The vertical, as well as the angular and ho.;,ontal nnovement can be controlled automatically by the computer control mounted in cabinet 13 or m~nll~lly by way of the co~ . and controls 18 shown in Figure 14.
Referring to FIG. 20, a positional schematic of saws 26, 40, 400, 500 and 600 in a home position is shown. Power saw 500 is mounted on a pivot point 512 in-line with axis 511 of saw motor 510. Pivot point 512 is located a rlict~n~e Phl from saw blade face S09 and a ~iiet~nre Hl from the xl-l~fe.~ncc. The dHyl-reference line lep.es~,.lLs the direction of linear motion of power saw S00. The x-,~re;ences of each saw is design~ted by the top-of-chain plane of the material conveyor 32, which is also the bottom plane of a board being p...Gessed by the assembly. Power saw 40 is mounted on a pivot point 139 distal from axis 41 of saw motor 80. Pivot point 139 is located a dict~nce Ph2 from saw blade face 82, a distance H2 from the x2-l~Çe.. nce, and a dict~nce Hc12 from axis 41. The dHx2-reference line ~ Jl.senls the direction of linear motion of power saw 26. Power saw 600 is mounted on a lS pivot point 612 in-line with axis 611 of saw motor 610. Pivot point 612 is located a distance Ph3 from saw blade face 609 and a fiict~nce H3 from the x3-reference. The dHy3-reference line l~ se~ the direction of linear motion of power saw 26. Power saw 26 is mounted on a pivot point 27 located distal from axis 41 of saw motor 80. Pivot point 27 is located a ~lict~nce Ph4 from saw blade face 83, a dict~nce H4 from the x4-reference, and a ~iict~nce Hc14 from axis 41. The dHx4-reference line r~ s~ the direction of linear motion of power saw 26. Power saw 400 is mounted on a pivot point 412 located in-line with axis 411 of saw motor 410. Pivot point 412 is located a dict~nce Ph5 from saw blade face 409, and a ~iict~nce H5 from the x5-lefc.e--ce. The dHx5- and dHy5-reference lines lc~ selll the direction of linear motion of power saw 400.

CA 0221~91~ 1997-09-19 WO 96129''~84 PCT~US96~03878 The vertical positioning capability of power saws 400, 500 and 600, ~ e.~ /ely, allow proceecillg of larger dim~ioned boards. For example, the h~liG~ lly-adjustable power saw 26 can readily accommod~te two-by-four boards, but cannot provide shallow-deep saw cuts in two-by-twelve boards. The Ihl~c-saw configuration of power saws 600, 26 and 400 on fixed-5 power-saw-carriage assembly 20 also enables complex board end ~ cesCi~p for trusses implc.llc.lLillg "scissor cuts."
Referring to FIG. 21a, a truss 700, assembled with various-sized com1e.;lor plates 701, implc.llc.lLng a scissor cut is shown. Referring to FIG. 21b, truss board 702 is illustrated i greater dletail. The scissor cut has a seat cut 704, a scarf cut 706, and a butt cut 708. Board 702 has a plurality of conse~;uli~ely numbered points: point-zero 710, point-one 711, point-two 712, point-three 713, point-four 714, point-five 715, and point-six 716. The location of these points are stored within the computer in cabinet 13 and used to process uncut boards. The points are defined in accordance with angle and dimensional data associated with a desired truss board. For convenience, the points are numbered clockwise beginning at the lower-left 15 point.
FIG. 22 is a flow chart depicting the general steps carried out to set the angular positions of the five power saws, the ho~;~o~ position of saws 26, 40 and 400, and the vertical position of saws 400, 500 and 600. Based upon the drawings of all the dimensions and angles of a truss to be cut with the sawing system, a predefined point associated with one 20 or two angles at each end of the board can be d~oterrnin~d FIGS. 23a-b and 24a-c serve to illustrate the positioning of the power saws to cut the truss board 702 (shown in FIG. 21b).
The saw blades of power saws 26, 40, 400, 500 and 600 are positioned utili7ing variations of a general algorithm. This algorithm takes into account the pivot-point positions of the saws with respect to the x-reference axis and the y--er.,.~nce axis, as shown in FIG. 20.
25 The general algorithm is:

CA 022l59l5 lss7-os-ls Wo 96/29184 PCT/US96/03878 of the saws with respect to the x-reference axis and the y-reference axis, as shown in FIG.
20. The general algorithm is:

XOFFSEr=T~

where:

Tx=(Ph)C~S(OM~ 2 ) -Hcl(cosOu) +dHX-Ph Ty= -(Ph)srn(OM- 2 ) +Hcl(sin~3u) +dHy+H

Angle -m is the angle between the x-reference and the face of the power saw blades.
In program flow block 802, the angle data and ~limPn~ion data are retrieved from the database associated with the particular truss board to be cut. Program flow block 804 assigns the saw cuts to the left side saws 500 and 40 for single cuts or double cuts accordingly. In the example shown in FIGS. 21a and 21b, a double cut is made on the left end of the board 702.
In program flow block 806, the position of the ~ignl~cl left side saws are d~ lllhled such that a ciict~nee from the saw blade edges to the hold-down and to the material conveyor is minimi~ed In other words, power saw blade 82 is positioned so as not to i~llelrere with material conv~yor. Power saw blade 508 has an upper-blade tip 514 that is positioned to extend s--fficiently past the board top edge 720 to cut through the board yet avoid i"~t;lrtlil~g with hold-down 34. An advantage of ~ illg the amount upper-blade tips of the saws extend past the top edge 720 is that the hold-downs 34 do not inle.rele with the processing of shorter truss boards.

WO 96~?9~4 PCTJUS96J03878 A s shown in FIG. 23b, hold-down 34 can be placed at about two-inches from the upper-blade tip 514. In the example provided, power saw 500 having a vertical adj~tmPnt is making the top cut. The dHyl co~ ensd~ion is de~~ ed by the following formula:

=dHY=TY+(Ph~)Sin(Ol~ 2)-(Hcl~)sin(~1~)-H~

mma~ .=dHy=Ty+(phl)s~ ~ 2 )-(Ncll)s~ )-N

where:
l~y=Y+(DL4/2-MINllPOFFSET)sinOl For the saw configuration present, minadj parameters for power saw 500 cannot be less than 10 about negative four-inches. Maxadj cannot be more than a positive twelve-inches. The dHy, up-down adjl-stmPnt is made in ten iterations beginning from the minadj value. Similarly, the dHxl in-out adj~l~tmPnt for saw 40 is ~lP-tprminp~l after blade 82 is oriented to an angle 192.
The dHx value, or X-offset, is the ~limP.n~ion from the y2-axis to the object point. In this example, the object point is first-point 711. Knowing this value, saw 40 is aligned to make 15 its cut by the following formula:

Y-T
dHX2 =XQFFSET T~

where:

Tx=(Ph2)cos(02 - 2 ) -HCI2(cos~2) +dNX2-Ph2 Ty= -(Ph2)sin(~2 ~ 2 ) +Ncl2(sin~2) +dNY2+H2 CA 022l~9l~ lss7-os-ls Wo 96/29184 PCT/US96/03878 In program block 808, the saw cuts are ~ignlod to the right side saws 26, 400 and 60 for single cut, double cuts or scissor cuts, acco~ gly. For the scissor cut shown in FIG.
21b, all the right side saws are ~ ignPrl for the cut. In program block 810, the positions of the a~ ned left side saws are ~le~ 1 such that a ~ t~n~e from the saw blade edges to S the hold-down and to the material conveyor is ...i..;...;,~-(l In this case, saw 400 is of plhll~y concern for illLe:lr~ g with hold-down 34. In other words, power saw blade 408 is posi-tioned so as not to illLe;lrere with material collveyor 34. Power saw blade 408 has an upper-blade tip 414 that is positi~n~ to extend snfficiently past the board top edge 720 to cut through the board yet avoid illL~lrt;lillg with hold-down 34. To position the saws, the seat-10 butt point elevation, or fifth-point 715 elevation, measured from the x-reference is deter-mined. A first dHx, or x-offset, value is the ~ t~nre from the fifth-point 715 to the y4-axis.
Based on this ~ t~nre, saw 26 is put into place using the following formula:

dHX4=Tx+ph4+Hcl4cc)s~4-ph4cos(~34- 2) 15 where:

T X+ (Y~r~

and where:

Ty=-Ph4sin(~34- 2)+Hcl4sinO4+dHy4+H4 With respect to positioning power saw 400, the scarf-butt point elevation, or fourth-point 714 20 elevation, is determined. Referring to FIG. 24c, the x_int value is deLellllined, which is length A minus length B. Based on this illÇollll~Lion and ~e angle f~5 of saw blade 408, the WO 9612~184 PCT/US96/0;~78 following formula is used to tll~t~rminP the dHy value and dHx value such that upper-blade tip 414 barely clears the top edge 720:

- d~S=TI-PhSCOS(~3S- 2)+~sc~s~s+Ph5 dNys=Ty-ph5s~ 5- 2)-~1~cin~s~N5 where:
Iy=Y-(DlA/2-MINllPOFFSET)sm05 l~c=X+(DIA/2 -MINllPOFFSEl~cos~s Program step 612 sets the carriage length between fixed carriage 20 and movable calliage 22.
The carriage length is set to position the movable c~,iage 22 so that the board is cut at the proper length. For example, saws 26 and 40, as shown in FIGS. 23a and 24b, respectively, are ~ign,od to make the bottom cuts for ~e scissor-truss board 702. The carriage length L
15 is the bottom edge length D plus the left offset F minus the right offset E.
Program step 814 parks the saw heads not used for processing the truss board.
Patching a head con~i~t~ of setting its height adj-l~tm~nt dHy, ho~ unLal adj--~tm~nt dHx, and angle ~, so that the saw blade is completely above our outside the board to be processed. In the scissor-cut example provided, all the heads are used to process the board 702, so none are 20 parked.
Program step 816 sets the height and hori~ol~Lal position of hold-downs 34 to avoid the saw blades while still le.~ i-.g close to the blades. Positioning is accomplished by CA 0221~91~ 1997-09-19 determining which saw on the fixed carriage 20 and the saw on the movable carriage 22 extend the furthest along the x-lcfe.el-ce axis. It is desirable to place the hold-downs as close as possible to the blade tips such that short truss board members can be processed.
Program step 818 physically positions the saws 26, 40, 400, 500 and 600 through the S mecll~nir~l appdldlus diccucsed earlier. Movable carriage 22 is driven into place, and hold-downs 34 are positioned according to the determinations made in program step 816.
In program step 820, the truss board 702 is processed through the setup. A plurality of boards can be processed in the configuration. When a new configuration is desired, the program steps shown in FIG. 22 are repeated with the new angle and dimension data.
From the foregoing, the various co.l.pone.. l part of an efficient sawing system are disclosed, with the enh~nçed capability of moving the power saws, as well as the in-feed material conveyors. With the provisions of the present invention, the various collll)o~ ll parts can be manufactured in a more cost efficient manner, and require less m~intPn~nce without sacrificing precision or accuracy. Accordingly, various modifications may suggest themselves 15 to those skilled in the art without departing from the spirit and scope of the invention, as defined by the appended claims. Also, those skilled in the art may prefer to utilize some of the features and advantages of the invention, without using all of the features. The invention is not to be ~ci,Ll--;Led to the specific forms shown, or the uses mentioned, except as to the extent required by the claims.

Claims (57)

What is Claimed is:

1. Apparatus for use in a sawing system for moving a power saw, the apparatus comprising:
a generally planar base;
a motorized power saw having a shaft secured to said base, said power saw having a saw blade secured about said shaft;
a rotatable shaft having a first end and a second end, said first end fixed to said base at a pivot point distal from a face plane of said saw blade and in substantial orthogonal relation with said power saw shaft for angularly moving said power saw to different angular positions with respect to an angular position of said rotatable shaft;
a computer-controllable pivot drive unit engaged with said second end of said rotatable shaft;
a carriage frame;
a suspension beam slidably suspended from said carriage frame such that said beam is longitudinally movable with respect to said frame and said rotatable shaft rotatably secured to said suspension beam;
at least one linear bearing secured to said mounting frame and suspending said suspension beam therefrom such that said beam is longitudinally movable with respect to said frame; and a computer-controllable suspension drive unit drivingly attached to said suspension beam in a spaced apart relation from said at least one linear bearing and secured to said mounting frame for longitudinally moving said beam a desired distance.

2. The apparatus of Claim 1 wherein said motorized power saw is on a first side of said suspension beam and said computer-controllable pivot drive unit is on an opposite side of said suspension beam, said power saw and said pivot drive unit in mechanical communication through said rotatable shaft.

3. The apparatus of Claim 1 further comprising:
at least one pair of cam followers having a spaced apart relation sufficient to slidably accept said suspension beam therebetween yet minimize a lateral movement of said suspension beam, said pair of cam followers secured to said frame.

4. The apparatus of Claim 1 further comprising:
a computing device electrically connectable to said computer-controllable pivot drive unit and said computer controllable suspension drive unit, and a program, for execution by said computing device, having an algorithm for calculating a longitudinal displacement of said suspension beam with respect to a reference point constant as a function of an angular position of said power saw.

5. The apparatus of Claim 4 wherein said algorithm is:

where:
D is the distance between said pivot point and a point perpendicular to said face plane of said power saw, h is the distance from said pivot point to a predefined point of a board, and ~ is said angular position of said blade of said power saw.

6. Canceled

7. Canceled

8. Canceled

9. Canceled.

10. The apparatus of Claim 1 further comprising:
a second generally planar base;
a second motorized power saw having a shaft secured to said second base, said second power saw having a second saw blade secured about said shaft;
a second rotatable shaft having a first end and a second end, said first end fixed to said second base at a pivot point distal from a face plane of said second saw blade and in substantial orthogonal relation with said second power saw shaft for angularly moving said second power saw to different angular positions with respect to an angular position of said second rotatable shaft;
a second computer-controllable pivot drive unit engaged with said second end of said second rotatable shaft;
a second carriage frame spaced apart from said first carriage frame;
a second suspension beam slidably suspended from said carriage frame such that said second beam is longitudinally movable with respect to said second frame and said second rotatable shaft rotatably secured to said second suspension beam, said second suspension beam orienting said second power saw in a direction opposite transverse transpose said first power saw;
at least one linear bearing secured to said second carriage frame and suspending said second suspension beam therefrom such that said second beam is longitudinally movable with respect to said second frame; and a second computer-controllable suspension drive unit drivingly attached to said second suspension beam in a spaced apart relation from said at least one linear bearing and secured to said second carriage frame for longitudinally moving said second beam a desired distance.

11. The apparatus of Claim 10 further comprising:
a computing device electrically connectable to each said computer-controllable pivot drive units and to each said computer controllable suspension drive units; and a program, for execution by said computing device, having an algorithm for calculating a longitudinal displacement of said first suspension beam with respect to a reference point constant as a function of an angular position of said first power saw and an angular position of said second power saw.

12. The apparatus of Claim 11 wherein said algorithm is:

where D is the distance between said pivot point of said first power saw and a point perpendicular to said face plane of said first power saw, h is the distance from said pivot point of said first power saw to a predefined point of a first end portion of a board, ~ is said angular position of said blade of said first power saw, D2 is the distance between said pivot point and a point perpendicular to said face plane of said second power saw, h2 is the distance from said pivot point of said second power saw to a predefined point of the board, and ~2 is said angular position of said blade of said second power saw.

13. Canceled.

14. Canceled.

15. A method of positioning a power saw having a shaft and a saw blade secured about the shaft, the method comprising the steps of:
fixing a first end of a rotatable shaft to the base at a pivot point distal from a face plane of the saw blade and in substantial orthogonal relation with the power saw shaft;
suspending a suspension beam from a carriage frame such that the beam is longitudinally movable with respect to the carriage frame;
guiding a bottom portion of the suspension beam with a pair of cam followers secured to the carriage frame;
mounting a drive motor drivably connected to a second end of the rotatable shaft through a gear reduction;
rotatably mounting said rotatable shaft through the suspension beam such that the first end of the rotatable shaft is on an opposite side of the suspension beam from the drive motor;
mounting the power saw to the base so that the saw blade is transverse to a longitudinal movement of the base;

16. The method Claim 15 further comprising the step of:
processing on a computer angular information on a computer related to an angle to be cut in a board with a correction factor algorithm; and determining the displacement for moving the suspension beam with respect to a reference point.

17. Canceled.

18. Canceled.

19. Canceled.

20. Canceled.

21. Canceled.

22. Canceled.

23. Canceled.

24. Canceled.

25. Canceled.

26. A computer-implemented method of orienting a power saw form making a cutin a workpiece through a predefined point, the power saw having a pivot point distal from a front face of a saw blade secured to a shaft of the power saw and in substantial orthogonal relation with the power saw shaft, the power saw having a distance D between the pivot point and the front face, the power saw rotatably mounted to a suspension beam and drivable by a computer-controllable pivot drive unit, the suspension beam mounted to a carriage frame such that the suspension beam is longitudinally movable with a computer-controllable suspension drive unit drivingly attached to the suspension beam and secured to the carriage frame with respect to the frame, the method comprising the steps of:
determining a vertical distance h from the pivot point to the predefined point on the workpiece;
selecting the angle ~ to position the power saw to cut the workpiece through the predefined point;
calculating a correction factor with a program executed on a computer using a correction factor algorithm with respect to the parameters D, h and ~ for moving the power saw with respect to a reference point for making the cut through the predefined point;
rotatably positioning the power saw to the angle ~ through the computer-controllable pivot drive unit; and longitudinally positioning the suspension beam with respect to a reference point according to the correction factor calculated with the program executed on the computer.

27. The method of Claim 26, wherein the algorithm is

28. Canceled.

29. Canceled.

30. A computer-implemented method of orienting at least a first and a second power saw positioned generally opposite and apart each other, said power saws for making a cut in a first end and a second end of a workpiece through a first and second predefined point, each power saw having a pivot point distal from a front face of a saw blade secured to a shaft of the power saw and in substantial orthogonal relation with the power saw shaft, each power saw having a distance D between the pivot point and the front face, and each power saw rotatably mounted to a suspension beam and drivable by a computer-controllable pivot drive unit, the suspension beams mounted to a carriage frame such that the suspension beams are longitudinally movable with computer-controllable suspension drive units drivingly attached to each of said suspension beams and secured to the carriage frames with respect to the frame, the method comprising the steps of:
determining for the first power saw a vertical distance h from the first power saw pivot point to the first predefined point on the first end of the workpiece;
selecting for the second power saw a vertical distance h2 from the second power saw pivot point to the second predefined point on the second end of the workpiece;
selecting the angle ~ to position the first power saw to cut the workpiece through the first predefined point;
selecting the angle ~ to position the second power saw to cut the workpiece through the second predefined point;
calculating a correction factor with a program executed on a computer using a correction factor algorithm with respect to the parameters D, h, ~, and D2, h2, ~2 for moving the first power saw with respect to a reference point for making the cut through the first predefined point;
rotatably positioning the first power saw to the angle ~ and the second power saw to the angle ~2 through the first and the second computer-controllable pivot drive units;

longitudinally positioning the first suspension beam through the first computer-controllable suspension drive unit with respect to a reference point according to the correction factor calculated with the program executed on the computer; and longitudinally positioning the second suspension beam with the second computer-controllable suspension drive unit with respect to a second reference point for making a cut through the second predefined point.

31. Canceled.

32. The method of Claim 30, wherein the algorithm is

33. Canceled.

34. A sawing system comprising:
a frame for supporting components of the sawing system, said frame having a backlongitudinally extending rail and a front longitudinally extending rail, said back rail elevated and substantially parallel to said front rail;
a stationary carriage mounted to said frame, said power saw carriage having a first and a second power saw for cutting stock fed to the sawing system, said first power saw pivotally mounted to said frame, said second power saw is spaced apart from said first power saw and is mounted to a longitudinally movable suspension beam slidably mounted to said stationary carriage and has a first pivot point distal from a face plane of a saw blade secured about a shaft of said second power saw and is in substantial orthogonal relation with said second power saw shaft;
a movable carriage longitudinally movable along said front rail and said back rail of said frame, said movable carriage having a third and a fourth power saw for cutting stock fed to the sawing system, said third power saw is mounted to a longitudinally movable suspension beam slidably mounted to said movable carriage and has a second pivot point distal from a face plane of a saw blade secured about a second shaft of said third power saw and is in substantial orthogonal relation with said third power saw shaft, and said first power saw pivotally mounted to said frame and spaced apart from said third power saw;
a hold-down mechanism associated with each said power saw carriage for exerting a downward pressure on stock fed to the sawing system;
a pair of chain-driven material conveyors, each of said conveyor associated with a respective said stationary and movable power saw carriage, each said conveyor supported on said back rail and on said front rail, whereby said pair of chain-driven material conveyors are angled upwardly from front to back, said material conveyors operate in conjunction with said hold-down mechanism for feeding stock to said power saws of said stationary and movable power saw carriage;
a common square drive shaft coupled to both said material conveyors for driving a respective feed chain of each said material conveyor, said material conveyors movable along said frame while remaining driven by said common square drive shaft, each said material conveyor having a square tubular drive member through which said square drive shaft passes for coupling a torque of said square drive shaft to said tubular drive member of each said material conveyor;
a chain take-up mechanism connected to a frontal portion of each said material conveyor, said take-up mechanism enclosed between opposing side cover plates and having means for adjusting a tension of said material conveyor chains through an access opening defined in each said cover plate for accessing said take-up mechanism whereby said material conveyors can be moved close together.

35. Apparatus for moving a power saw in a sawing system comprising:
a substantially planar base;
a motorized power saw having a saw blade secured to said base, said motorized power saw having a first axis of rotation about which said saw blade rotates and having a second axis of rotation on said base distal from a face plane of said saw blade and substantially aligned with said first axis of rotation about which said motorized power saw tilts;
a rotatable shaft having a first end and a second end, said first end fixed to said base at said second axis of rotation, said rotatable shaft adapted to correspondingly impart rotation to said motorized power saw about said second axis of rotation;
a computer-controllable pivot drive unit engaged with said second end of said rotatable shaft for angularly moving the motorized power saw to different angular positions;
a carriage frame;
a vertical lift support mounted to said carriage frame;
a lift assembly secured to said base for linearly moving said power saw in a substantially vertical direction, said lift assembly having a sled plate slidably mounted to said vertical lift support;
and a computer-controllable lift drive unit drivably attached to said lift assembly;
a suspension beam slidably suspended from said sled plate for longitudinally moving said power saw with respect to said vertical lift support, said rotatable shaft rotatably secured through said suspension beam such that said first end of said rotatable shaft extends on a first side of said suspension beam and said second end extends on an opposite side of said suspension beam;
a computer-controllable beam drive unit attached to said suspension beam for longitudinally moving said suspension beam.

36. The apparatus of Claim 35, further comprising:
a computer having an executable program for calculating displacement of the suspension beam with respect to an angular position of the power saw, said computer electrically connectable to said beam drive unit for longitudinally positioning said power saw and to said lift drive unit for vertically moving said power saw.

37. Canceled.

38. Canceled.

39. Canceled.

40. Canceled.

41. Canceled.

42. Canceled.

43. Canceled.

44. A sawing system comprising:
a frame having a longitudinally extending back rail and a longitudinally extending front rail, said back rail elevated and substantially parallel to said front rail;
a saw carriage mounted to said frame;
a vertical support mounted to said saw carriage;
a sled plate slidably mounted to said vertical support;
a first power saw having a rotatable shaft with a first end and a second end, said first end fixed to a pivot point substantially aligned with a shaft of said first power saw and said rotatable shaft rotatably mounted to said sled plate;
a computer-controllable lift drive unit secured to said sled plate and drivably engaged to said vertical support;
a first computer-controllable pivot drive unit mounted to said sled plate, said pivot drive unit engaged with said second end of said rotatable shaft;
a second power saw spaced apart from said first power saw slidably mounted to said carriage on a suspension beam for longitudinally moving said second power saw with respect to said carriage and a computer electrically connected to said first and said second power saws, said computer having an executable program for computing a longitudinal displacement of said first power saw with respect to an angular position of each said firs and second power saws.

45. The sawing system of Claim 44, further comprising:
a movable saw carriage spaced apart from said first saw carriage adjustably mounted about said frame for varying a distance to said first saw carriage; and a third power saw positionably mounted on a second longitudinally movable suspension beam secured to said second carriage for longitudinally moving said third power saw with respect to said movable saw carriage, said third power saw electrically connected to said computer such that said third power saw is positionable by the computer.

46. Canceled.

47. The sawing system of Claim 45, wherein said computer controls a positioning of said movable saw carriage along said frame for cutting a board to length.

48. Canceled.

49. Canceled.

50. Canceled.

51. A sawing system comprising:
a frame having a longitudinally extending back rail and a longitudinally extending front rail, said back rail elevated and substantially parallel to said front rail;
a first and a second saw carriage, at least one said saw carriage mounted to said frame such that a distance between said carriages can be selected;
a first power saw assembly having a power saw with shaft for receiving a saw blade about an end of said shaft, said first power saw assembly mounted to said first saw carriage and having a pivot point distal from a plane orthogonal to said shaft end and in substantial orthogonal relation with said power saw shaft for angularly moving said first power saw to different angular positions;
a second power saw assembly having a second power saw with a shaft for receiving a saw blade about an end of said shaft, said second power saw assembly mounted to said first saw carriage and spaced apart from said first power saw assembly, said second power saw having a pivot point distal from a plane orthogonal to said shaft end and in substantial orthogonal relation with said second power saw shaft for angularly moving said second power saw to different angular positions and said second power saw longitudinally positionable with respect to said first saw carriage;
a third power saw assembly having a third power saw with a shaft for receiving a saw blade about an end of said shaft, said third power saw assembly mounted to said second saw carriage and having a pivot point distal from a plane orthogonal to said shaft end and in substantial orthogonal relation with said third power saw shaft for angularly moving said first power saw to different angular positions with respect to an angular position of said rotatable shaft;
a fourth power saw assembly having a fourth power saw with a shaft for receiving a saw blade about an end of said shaft, said fourth power saw assembly mounted to said second saw carriage and spaced apart from said third power saw, said fourth power saw having a pivot point distal from a plane orthogonal to said shaft end and in substantial orthogonal relation with said fourth power saw shaft for angularly moving said fourth power saw to different angular positions and said second power saw longitudinally positionable with respect to said second saw carriage;
a fifth power saw assembly having a fifth power saw with a shaft for receiving a saw blade about an end of said shaft, said fifth power saw assembly mounted to said second saw carriage and spaced apart from said third power saw, said second power saw having a pivot point distal from a plane orthogonal to said shaft end and in substantial orthogonal relation with said fourth power saw shaft for angularly moving said fourth power saw to different angular positions and said second power saw longitudinally and vertically positionable with respect to said second saw carriage;
a computer electrically connectable to each said power saw assembly, said computer having a program with a database having selectable cuts and a correction factor algorithm for correcting a longitudinal position of each of said second, fourth and fifth power saws with respect to a change in angular position of said second, said fourth and said fifth power saws,said computer for positioning each said saw of each said assembly according to said program; and a stock feed system for feeding stock between said first and second saw carriages.

52. Canceled.

53. Canceled.

54. a computer-implemented method of orienting a vertically adjustable power saw having a saw blade, the power saw mounted to a carriage to make a cut in a workpiece through a predefined point, the method comprising the steps of:
determining a vertical offset of the power saw such that an upper tip of the saw blade barely extends past an upper edge of the workpiece while cutting through the predefined point; and positioning the saw to make the cut.

55. The method of Claim 54 wherein the step of determining the vertical offset further comprises the steps of:
determining a maximum vertical adjustment value of the power saw with respect to a top surface of the workpiece;
determining a minimum vertical adjustment value of the power saw with respect to a bottom surface of the workpiece; and conducting a plurality of iterations between the maximum and the vertical adjustment values until the tip barely extends past the upper edge of the workpiece.

56. The method of Claim 55 wherein the step of determining a minimum adjustement value is calculated using the algorithm:

where:

57. The method Claim 55 wherein the step of determining a maximum adjustment value is calculated using the algorithm:
where: