Method and apparatus for feeding an edger

An edger feeding apparatus and method of placing flitches in position to be fed into an edger with minimal spacing between successive flitches and with flitches oriented and the edger adjusted so as to yield a maximum value of lumber from each flitch. The edger feeding apparatus may include a scanning system for creating and storing a digital three-dimensional model of each flitch. The apparatus and method may also include a control computer and its use for determining the optimum position for feeding each flitch into the edger to produce the most valuable yield of lumber from the flitch.

BACKGROUND OF THE INVENTION

The present invention relates to processing wood products, and in particular to apparatus and a method for feeding flitches into an edger so as to optimize production of marketable lumber from the flitches.

When a log is sawed in the process of producing lumber a cant or cants are produced from the central portion of the log by removing slabs and flitches from sides of the log, usually in a way to maximize the marketable amount of lumber that can be produced from the cants. Flitches removed from the sides of the log may include wane that can be removed by an edger to obtain marketable lumber from each flitch.

An edger typically includes several parallel circular saw blades spaced at standard distances, or in some cases adjustably spaced, along an arbor. Sets of powered bottom rollers and press rollers are arranged to run a flitch longitudinally through the edger saws to produce standard-sized boards and remove edge portions that have no commercial value as lumber.

In conventional practice, an edger operator manually places each flitch onto infeed rollers of an edger in a position estimated to provide the maximum amount of marketable lumber from a particular flitch, in some cases with the assistance of laser guidelines. In such conventional edger operation flitches are delivered serially and longitudinally into a preliminary position where the edger operator must adjust its position and orientation before edger infeed rollers pinch the flitch and deliver it into the saw blades. As a result, there is a significant gap between the tail end of a flitch being sawn in the edger and the head end of the next flitch to enter the edger saw blades.

As a result of the gaps between flitches being fed into an edger, there may be a significant delay, or dead time, of as much as a few seconds between flitches going through an edger. The output of an edger could be significantly increased by reducing the space between the tail of one flitch and the head end of the next flitch, thus reducing the dead time between successive flitches.

What is desired, then, is a way to reduce the dead time between flitches being sent through an edger, and at the same time to maximize the production of marketable lumber from flitches by ensuring that they are located and oriented, as they pass through an edger, so as to produce boards calculated to result in the maximum value of marketable boards from each flitch.

SUMMARY OF THE INVENTION

As an answer to some of the needs explained above, an edger feeding apparatus and a method of feeding flitches into an edger with only a minimum spacing and dead time between successive flitches are disclosed hereinbelow and defined in the claims that form a part of the disclosure.

In one embodiment of the apparatus disclosed herein, a feed line, also called a scanner and carriage assembly, moves individual flitches laterally, in a direction transverse to the length of each flitch, and a scanning system associated with the feed line measures each flitch and creates and stores a digital three-dimensional model of each flitch. The flitches are moved to a transfer ready position at an outfeed end of the scanner and carriage assembly in readiness to be transferred laterally to an edger ready position near the infeed end of an edger and a small distance above the edger infeed mechanism. Transfer of successive flitches to the edger infeed mechanism is accomplished in a much shorter time than by moving each flitch longitudinally after another.

In one embodiment of the apparatus, a control computer keeps the digital models of the flitches in memory in a queue specifically identifying the three-dimensional model of each flitch. Based on, for example, tabulations of the commercial values of different sizes and qualities of boards, the control computer determines how each flitch should be located and oriented on the edger infeed mechanism as it proceeds longitudinally through the edger, to produce the most valuable yield of lumber from that flitch.

In one embodiment of the apparatus, each flitch is stopped in a transfer ready holding position and then is engaged to be moved by a charger subassembly. Each charger subassembly includes a lower flitch carrier member spaced apart from another along the length of the flitch, and each flitch carrier member includes a turntable portion which can engage the bottom of the flitch. A respective upper contact pad is moved down by an actuator to press the flitch onto the turntable portion of the flitch carrier member. The upper contact pad is positioned located directly above the turntable portion of the flitch carrier member. The flitch carriers are moved to carry the flitch laterally to the edger ready position, in a desired location and orientation above the edger infeed mechanism in a very short time. Each of the upper contact pads is controlled to move together with and remain aligned with the turntable of its corresponding flitch carrier member as the feed forks and contact pads move the flitch to the desired edger ready position with respect to an infeed mechanism of the edger that will result in the maximum commercial value of the boards that can be obtained from that flitch.

For example, an edge portion may be removed from each edge of a flitch, leaving a single dimensional board with four flat sides. For another flitch the control computer may direct the feed forks to orient and position the flitch where the edger will produce one board with four flat sides and another, lower grade, board with one edge surface including acceptable wane, depending upon the shape of the digital model of the flitch that has been produced by the control computer as result of scanning the flitch. Yet another flitch may be oriented and positioned so that when it proceeds through the edger two boards with acceptable wane will be produced.

In one embodiment of the apparatus, when a flitch is positioned above the infeed mechanism, a set of tipples adjacent the infeed mechanism are moved upward and into supporting contact with the underside of the flitch. At the same time, an infeed press roller associated with a tipple is lowered into contact with the upper side of the flitch, so the flitch is held in the correct location. Once the flitch has been grasped and is held by the tipples and the press rollers the flitch carrier members and the upper contact pads release the flitch and are retracted. The infeed press rollers keep the flitch in the desired orientation and location established by the carrier members and pressure pads and in contact with and supported by the tipples.

Once a preceding flitch has been moved far enough toward the edger saws the tipples are lowered and the accompanying infeed press rollers are raised, moving the flitch in the direction of movement of the infeed mechanism and lowering the flitch onto the infeed mechanism. In one embodiment of the invention the control computer takes into account the time that may be required to adjust the positions of the edger saw blades after the preceding flitch has cleared, while the flitch is supported and held by the tipples and press roller. The flitch is then lowered onto the edger infeed mechanism at a calculated time and in a controlled fashion so as to come into contact with the edger infeed mechanism in the position and orientation that has been calculated by the control computer to result in producing boards of optimum value from that flitch.

In accordance with one aspect of a method disclosed herein, then, each of a series of flitches is scanned, a queue of three-dimensional models is produced, and the control computer calculates a position and an orientation for each flitch so as to feed the flitch into the edger and thus produce the optimal yield of lumber from the flitch. When a flitch reaches the final position on the feedline, or scanner and carriage assembly, where it is the next in line to be sent through the edger, it is moved by the flitch carrier members to a predetermined orientation and position above the edger infeed mechanism. When a preceding flitch has moved out of the way the flitch is engaged by tipples and pressure rollers and the flitch carrier members are retracted.

After a preceding flitch has moved a calculated distance toward the edger saws the flitch may be lowered onto the edger infeed chain and moved to where it can be engaged by infeed rollers of the edger. If the flitch is to be sawn into a different number of boards or into boards of widths or locations within the flitch that are different from the preceding flitch the amount of time required to adjust the edger saws is taken into account in determining when to move the flitch from the ready position to be engaged by the edger infeed mechanism.

The foregoing and other objectives and features of the invention will be more readily understood upon consideration of the following detailed description of the invention taken in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring first toFIGS. 1-4of the drawings that form a part of the disclosure herein, an edger20has an edger infeed mechanism22arranged to deliver a flitch of wood24,26,28, or30, etc. into the edger20. The edger20includes a set of edger saws31that are spaced apart from each other so as to produce a board or set of boards from a flitch24, etc., while removing bark-covered wane portions of the flitch that are of no commercial value as lumber. The edger infeed mechanism is controlled and operated by various sensors and servo systems shown schematically inFIG. 19.

A scanner and carriage assembly32, that also may be called a feedline, has a structural frame34oriented to deliver flitches24,26, etc. to the edger20by moving each flitch laterally, that is, in the direction of the arrow36, perpendicular to the length38of each flitch24,26, etc. The flitches are arranged side-by-side, lying flat and with their lengths oriented generally parallel with the arrow40, indicating the direction in the direction of which each flitch will pass longitudinally through the edger20. An end of each flitch that will be the leading end41as the flitch enters the edger is aligned with a lumber line42, at the right-hand end of the scanner and carriage assembly32as seen inFIG. 1. The flitches may be loaded onto the scanner and carrier assembly32manually or by conventional loading apparatus that need not be disclosed herein.

Depending upon the amount of manual labor that will be acceptable, the scanner and carriage assembly32may include a scanner (not shown) capable of discovering whether a wane side of a flitch is up or down. A flitch turning mechanism46mentioned inFIG. 18A, may be included in the feed line assembly32to turn flitches over as necessary for the wane side48of each flitch24, etc, to face upward. Such a mechanism is well known and need not be described herein. Flitches located on the scanner and carriage assembly are desirably, oriented with the narrower, or waned, face of each facing upward to be measured by the scanner system44in determining how to edge the flitch.

The frame34of the feed chain or scanner and carriage32assembly or scanner and carriage30includes a group of feed rail assemblies50that are oriented horizontally and parallel with each other, separated from one another by a distance52that is somewhat less than the length of the shortest flitch intended to be fed to the edger20. For example, the feed rail assemblies50may be spaced apart from each other by a distance corresponding to a standard board length intended to be produced. As shown inFIG. 1, there are four feed rail assemblies50in the scanner and carriage assembly32.

Endless loop feed chains54of which there are four shown inFIG. 1, are engaged with appropriate sprockets so as to move in respective parallel vertical planes. The endless feed chains54are arranged to be driven synchronously by drive sprockets carded on a chain drive shaft58, as best seen inFIG. 3. An upper portion of each of the endless chains54may be disposed horizontally and ride along the top of a respective one of the feed rail assemblies50to support flitches24,26, etc. and move them along the feed rail assemblies50toward the edger infeed mechanism22, spaced apart from each other by a desired distance. The feed chains54are driven to move continuously to carry the flitches24,26, etc. toward the edger infeed mechanism22.

Six sets of hooks60, seen inFIG. 1, extend across the direction of movement of the feed chains. They are carried on pivoted arms62and are arranged to be raised and lowered periodically to let each flitch24,26, etc. move in steps through predetermined distance along the scanner and carriage assembly32toward the edger infeed mechanism22, and to keep the flitches separated from each other. When a set of hooks60is raised and obstructs one of the flitches the feed chains54continue to move, but the links of the feed chains preferably have smooth straight outer surfaces that can slide along the bottom face of a flitch24, etc. without causing damage when the flitch is held stationary by one of the sets of hooks60. At the same time, however, the flitches24,26,28, etc. are engaged by the feed chains54with sufficient friction that each flitch is carried with negligible slippage when the flitch is not obstructed by a set of the hooks60.

As may be seen inFIG. 1, there may be six sets of hooks, spaced apart by a convenient distance such as 30 inches that may be designed accordingly to the size of flitches installed to be handled. As a flitch is carried along the scanner and carriage assembly32it is stopped momentarily at each set of hooks60, which may be called hook stop #1, or hook stop #2, etc. Various functions may be carried out at each hook stop or between one hook stop and the next, as will be explained in greater detail below.

The arms62carrying the ones of a set of hooks60may all be mounted on a shaft64extending transversely of the scanner and carriage, or feed line, assembly, thus parallel with the length of a flitch on the scanner and carriage assembly. Each such shaft64may be rotated through a few degrees in either direction by a respective lever66that is moved in either direction by suitable means such as inflation and deflation of the ones of a respective pair of airbags68, for example, as may be seen inFIG. 3.

The flitch measuring scanner system44, not shown in detail, is supported on a scanner support structure70extending above the scanner and carriage assembly32. The scanner support structure70is long enough to permit passage of the longest flitch intended to be handled by the edger infeed mechanism. The scanner system44may include a scanner array72of several laser scanners, and is located between hook stop #4 and hook stop #5 along the scanner and carriage assembly32, where each flitch24,26, etc. can be scanned precisely as it is carried along the feed rail assemblies50by the feed chains54. The scanner array72may, for example, measure a flitch on a grid of points spaced at 0.035″×0.035″ separation on all surfaces of the flitch. The scanner array72is connected functionally to a control computer74, as shown inFIG. 19. Digital data derived from scanning each flitch24,26, etc. is delivered to the control computer74, as by a suitable data cable (not shown).

The control computer74is adapted to receive the digital data from the scanner array72and to compile it as a digital three-dimensional model, such as a wireframe model, of each flitch. The three-dimensional model of a flitch may preferably be prepared to a resolution of 0.001 inch, to identify the boundaries of the flat upper face of each flitch, where the flitch begins to wane, and the control computer74utilizes the digital three-dimensional model as a basis for deciding what parts of the flitch should be removed by the edger20. An optimizer section76of the control computer74incorporates a database which may include a tabulation of many different sizes, types, and grades of lumber and the current value of each. The control computer74may be programmed to determine from the three-dimensional model what boards of which grades can be produced from a particular flitch24, for example, which parts of the flitch should be removed by the edger and how to cut the remaining portion of the flitch into pieces which can result in an optimum value of marketable lumber. A sawing solution is then developed by the control computer74and conforming instructions and data may be communicated among the various elements of the edger20, the scanner and carriage assembly32, and the edger feed mechanism22using a programmable logic controller77so that the flitch will be sawed accordingly by the edger20. The sawing solution may include instructions to require the edger to adjust the positions of individual ones of the various saw blades.

The digital three-dimensional flitch models are retained in digital memory by the control computer74, and are coordinated with data from the feed chains54, making three-dimensional model of each flitch24,26,28, or30, etc, the size and shape of each flitch available for use by the control computer74when the flitch reaches a transfer ready position78, in hook stop #6, at the outfeed end of the scanner and carriage, or feedline, assembly32.

A charger assembly88is located at the outfeed end of the scanner and carriage assembly32to transfer each flitch to an edger infeed mechanism. The charger assembly includes a charger subassembly82,84,86, and88, each conveniently associated with one of the feed chains54, The charger subassemblies for convenience will be called charger sets numbers1,2,3, and4, as seen in right-to-left order inFIG. 1. Each charger set82, etc, includes a respective lower charger beam90supported by the frame34of the scanner and carriage assembly32, and each such beam90is attached to the frame34by a pivot92near a rear, or inner, end of the beam90. An elongate charger lower flitch support member94is mounted to move along a slide track extending along to the lower charger beam90. An endless chain or toothed belt98is disposed as a loop encircling around a sprocket99at an outer end of the beam90and a sprocket100on a shaft of a servo motor102mounted at the inner end of the beam90. The belt98is connected so as to move the charger lower flitch support member94longitudinally along the slide track as controlled by the servo motor102. The servo motor is preferably capable of being controlled by the control computer74to move the endless belt to position the lower charger flitch support member94precisely, to an accuracy of ±0.001 inch.

Each of the elongate charger lower support members94desirably has a portion104near its outer end that may be called a turntable. The turntable104may be a set of concentric circular ridges extending proud of the surrounding surface of the respective lower charger member with a height of, for example, 0.020 inch, that will provide a reasonably secure grip on a bottom face of a flitch, without noticeably marring the surface of the wood. With a charger lower flitch support member94in the retracted position, a flitch24, etc. in the transfer ready location78at hook stop #6 is directly above the turntable of the feed fork.

An upper charger support structure106that is part of each charger set82or84, etc. extends toward the scanner and carriage assembly32from a support frame structure at a rear side of the edger infeed assembly22. An endless belt108extends horizontally along the upper charger support structure106, looped around a sprocket110at an outer end of the upper support charger structure106and a drive sprocket112mounted on a clamp pad positioning servo motor114at an inner end of the upper support frame structure, A clamp pad actuator116that may be an air cylinder-and-piston assembly is mounted on a slide track118extending horizontally along the upper support structure106. The clamp pad actuator116is connected with the endless belt108so that the clamp pad servo motor114controls its position along the slide track118under the control of the computer74with the same degree of precision by which the lower charger flitch carrier member94is controlled, so as to keep the actuator116located above the turntable104. A clamp pad120is carried on a moveable member of the clamp pad actuator116, and is thus kept directly above the center of the turntable104. The clamp pad120is arranged to move vertically so as to press a flitch24,26, etc. down onto the turntable104of the lower flitch support member94. It will be understood that either an air cylinder or another convenient type of motor such as an electric actuator or a hydraulic cylinder-and-piston assembly could be used as the clamp pad actuator116.

The lower charger beam90of each charger set82,84, etc. can be moved through a small angle about its pivot92, by a motor122such as an air cylinder and piston mounted on the frame of the scanner and carriage assembly and linked to an outer end of the beam90. By lowering the outer end of the beam90, the outer end of the charger lower flitch support member94can be lowered a small distance, for example about ½ inch, to be clear of the bottom face of a flitch24,26, etc. in the transfer ready position78at the outfeed end of the scanner and carriage assembly32until the turntable104and clamp pad120of the charger set82, etc. is in a required position and is intended to engage the flitch at the middle123of its width. When the charger set82, etc. is correctly located the motor122can raise the outer end of the lower flitch support member94, bringing its turntable104into contact with the flitch that is ready to be transferred. At the same or shortly later time the clamp pad120can be lowered against the upper face of the flitch.

The edger infeed mechanism22may include an endless edger infeed chain124arranged as a loop around suitable sprockets, a drive sprocket126and an idler sprocket128, and driven continuously in a vertical plane perpendicular to the infeed chains of the scanner and carriage assembly32so as to carry a flitch24, etc. longitudinally into the edger20. An upper run130of the edger infeed chain124may extend along and ride upon a suitable horizontal support rail132. The edger feed chain124may be a roller chain with the outer edges of the side plates of each link having a sawtooth shape, as shown in the inset inFIG. 10, intended to engage a bottom surface of a flitch24, etc. firmly but without noticeable marring, and the edger infeed chain may be referred to herein as a sharpchain124.

A respective tipple134is associated with each of the charger sets82,84,86, and88, and each tipple will be referred to separately by the member of the charger set with which it as associated, Each tipple is mounted on a respective tipple shaft136extending horizontally and perpendicular to the plane of the edger infeed chain124and thus parallel with the direction of movement of flitches along the scanner and carriage assembly32. The tipples134may be generally planar, extending radially outwardly away from the respective tipple shafts136. The tipples134have outer margins138that may have roughened or textured surfaces intended to engage a bottom face of a flitch frictionally.

A respective infeed press roller140may be mounted for rotation about the axis perpendicular in the place of the sharpchain124and may be carried on a support arm142attached to each of the upper charger support beams106on its upstream side, further from the edger20and opposite the location of the associated clamp pad actuator116. The support arm142may be arranged to pivot up and down about a horizontal pivot axis144that may also be perpendicular to the plane of the edger infeed sharpchain124. A suitable motor146such as an air cylinder-and-piston assembly is arranged to raise and lower the edger infeed press roller140to press a flitch24, etc, down against a tipple134in the edger ready position and also while lowering the flitch onto the upper130of the sharpchain124, and then to keep the flitch in contact with the sharpchain124as the flitch is delivered into the edger20.

The tipple shafts136are located beneath the infeed press rollers140, allowing each of the tipples134to be rotated, between a lowered position as seen inFIG. 4, alongside the upper run130of the edger infeed sharpchain124, and a raised, generally upright, position as shown inFIG. 12, in which an outer margin138of each tipple is located above the sharpchain124and can bear upon a bottom face of a flitch supported on the charger lower flitch support member94. The shaft of the #1 tipple can be rotated by an associated bell crank and motor148, while the shafts of the #2, #3, and #4 tipples have respective bell cranks149all linked together and controlled by motor150, so that the #2, #3, and #4 tipples can all be raised or lowered simultaneously.

Suitable sensors such as photocells152,154may be located respectively a short distance upstream from each of the #1 tipple and the #2 tipple, in positions enabling the sensors to recognize that a tail end162of a flitch is passing the respective one of the tipples134.

Under digital control from the control computer74, each lower flitch carrier servo motor102and the associated clamp pad actuator positioning servo motor114are operated synchronously to move a respective end of a flitch24, etc. from the transfer ready position78over a distance determined by the control computer74on the basis of the digital three-dimensional model of the particular flitch. A flitch thus can be moved from the transfer ready location78toward a calculated edger ready position156directly above the sharpchain124of the edger infeed mechanism22. As shown inFIGS. 11A and 11B, the control computer74causes each charger set82,84, etc. to move a respective end of a flitch a distance calculated to place the flitch in a required location and orientation above the edger infeed sharpchain124, ready to be carried to the saws31of the edger20and sawn into a board or boards that will maximize the value of the lumber cut from each flitch.

The sequence of steps for carrying flitches through the edger feed apparatus and the edger is shown in a flow chart embodied inFIG. 18. Communication connections between key positions of the systems are shown inFIG. 19, and an example of the timing sequence of actions in a cycle of handling a flitch is diagrammed inFIG. 20, The actions shown inFIG. 20will be noted herein by step numbers in parentheses. A flitch may be placed flat on the scanner and carriage apparatus32with an end158of the flitch that is eventually to be the leading end of the flitch aligned with the lumber line42at the right end of the scanner and carriage assembly32. The feed chains54are continuously in motion and carry the flitch30to hook stop #1, where the first set of hooks60engage the leading edge of the flitch and align the flitch30in the full taper orientation. At an appropriate time, ultimately as a result of a flitch being transferred away from hook stop #6, the set of hooks of hook stop #1 will be dropped allowing the flitch to move to hook stop #2, where flitch28is shown inFIG. 1. At each hook stop sensors will detect when the hooks60at the next subsequent hook stop are lowered so that a preceding flitch is starting to move away leaving space for the flitch being held at the lower-numbered hook stop, whose hooks60will then be lowered in response. As soon as a flitch has moved clear of a hook stop the hooks60are again raised to stop the next flitch. When the hooks60of hook stop #2 are dropped, the feed chains carry the flitch to hook stop #3 where it is engaged and stopped by the again-raised hooks60at hook stop #3. While moving between hook stop #2 and hook stop #3 the flitch26may have been scanned by a relatively simple scanner (not shown) to determine whether the wane is oriented up or down, and the determination will have been transmitted to the control computer74. Between hook stop #3 and hook stop #4 there may be a flitch turner selectively operative to turn up the wane side of a flitch if necessary. If the wane face is down the flitch turner will engage the flitch and turn it over to bring the wane face to the top. If the wane is already facing upward the control computer74will cause the feed chains54to carry the flitch on to hook stop #4, carrying the flitch so its leading edge contacts the hooks60and the flitch is thereby placed into a full taper orientation.

When the hooks of hook stop #4 are lowered the feed chains54carry the flitch through the scanner support structure70, and the upper and lower scanner arrays72measure the flitch and transmits scanner data to the control computer74, enabling the control computer to generate the digital three-dimensional model of the flitch. When the flitch just scanned reaches hook stop #5 the flitch is retained until a preceding flitch at hook stop #6 has been engaged by the charger mechanism80and is being transferred toward the edger ready position156. When the charger mechanism80has carried a proceeding flitch clearly away from the transfer ready position at hook stop #6 the hooks of hook stop #6 are raised to stop the flitch being moved from hook stop #5 in the transfer ready position in hook stop #6 at the outfeed end of the scanner and carriage assembly as shown inFIG. 5.

The feed chains54thus eventually carry each flitch24,26, etc, to the transfer ready position78at an outfeed end of the scanner and carriage assembly32at hook stop #6, where a charger assembly receives the flitch and moves it to the edger ready location156above an edger infeed mechanism22arranged to carry the flitch into the edger20.

In the transfer ready position78, the desired set of hooks60of hook stop #6 stop the flitch24and establish a full taper orientation, located where the flitch can be grasped to be moved to the desired orientation in the edger ready position and location156from which it is to be moved onto the edger infeed mechanism22. With the flitch in the transfer ready location78, at least a pair of the elongate charger lower flitch support members94, are located beneath the flitch in a retracted position along the slide track on the beam90.

When the flitch24has arrived at hook stop #6 it is ready for the charging sequence to be performed as directed by the control computer74. This begins as shown inFIG. 3, with each charger set82,84,86, etc. spanned by the length of the flitch24being moved to the position of the centerline123of the flitch, as determined from the three-dimensional digital model. With the lower flitch support member94lowered and the clamp pad120raised. Based on the digital three-dimensional model of the flitch24developed by the control computer74, each lower flitch support member94is moved along the beam90by the servo motor102to place the turntable104beneath the longitudinal centerline123of the flitch24, with the lower charger flitch support members94in their respective lowered positions. The lower flitch support members94can then be raised to bring the turntable104into contact with the bottom face of the flitch, as shown inFIG. 5(step1), and the clamp pads120can also be lowered onto the upper face of the flitch (step2). Depending on the sawing solution the appropriate charger sets (depending on the length of the flitch), engage the flitch24. The clamp pads of the #1 charger set82and of the charger set88nearest the opposite end of the flitch24are lowered to press on the top face of the flitch, but the clamp pads of a charger set between those charger sets are not lowered to press on the flitch. Once this has been accomplished the hooks60of hook set #6 are lowered (step3).

When a previous flitch has been carried on the sharpchain124far enough into the edger20for press rollers121within the edger20to grip the previous flitch, the press rollers140of the charger sets #2, #3, and #4 are raised (step4). When the tail end162is detected passing a sensor such as photocell152at the #1 charger set82the infeed press roller140at the #1 charger set82is raised, providing clearance above the sharpchain124to receive the flitch24being supported by the charger sets82and88at the transfer ready location. While the press rollers140are being raised the charger sets are briefly held (step5) before moving the flitch24to the edger ready position156.

When the space above the tipples134is cleared the two engaged charger sets may move by slightly different distances away from the transfer ready location78and toward the opposite side of the edger infeed mechanism22, moving the flitch24to the edger ready position156above the sharpchain124of the edger infeed mechanism in which the desired saw cut lines are parallel with the sharpchain124and where the flitch is offset laterally as necessary to rest in an optimal transport position on the sharpchain (step6).

As the flitch24moves clear of the transfer ready position78the hooks60of hook stop #6 are raised (step7). When a flitch24has been carried by the lower flitch carrier members to the edger ready position in the calculated location and orientation above the sharpchain124of the edger infeed mechanism22it is held there until a preceding flitch has been moved far enough into the edger20so that none of the preceding flitch remains above any of a set of tipples134, as inFIG. 14. The tipples134are then rotated to their raised positions (steps9,15) in which a portion of each tipple134extends upward on each side of the sharpchain124, and the outer margin surfaces138of the tipples bear against the underside of the flitch24and support the flitch in the edger ready position156established by the charger assembly80. The tipples may thus lift the flitch24slightly. The edger infeed press roller arms142are then pivoted downward bringing the infeed press rollers140into contact on the upper face of the flitch, urging the flitch against the outer margin surfaces138of the tipples134(step10).

Once the flitch24is supported by the tipples134, the lower charger beam actuator122is retracted to lower the lower flitch carrier members94a small distance from the lower face of the flitch, and the hold down pads120are raised from the upper face of the flitch (step11), The flitch carrier motors102and hold down clamp pad carrier motors114are then operated to retract the lower flitch carrier members and move the clamp pad actuator116toward the transfer ready position78so as to be clear of the flitch24and ready to engage the flitch26when it is moved into the transfer ready position by the next cycle of the scanner and carriage assembly32(steps12,13).

The flitch24is then held between the tipples134and the edger infeed press rollers140as shown inFIG. 8for at least a long enough time to provide an optimum end gap, enough separation between the tail end of the preceding flitch and the leading end41of the current flitch24for the preceding flitch to be sawn and moved clear of the saws31within the edger20, before the current flitch engages the saws31. Additionally, lowering the current flitch24must be delayed long enough to permit any relocation of the sawblades on the saw arbor that may be required in accordance with the sawing solution determined by the control computer74.

Once the charger lower flitch support members94and clamp pad120and their actuators116have moved away from the flitch24the tipples134are not obstructed and are clear to be rotated downward. When the sawing solution for the flitch24being moved laterally into the upper edger ready position156calls for it to be sawn by the edger20into the same number and sizes of boards as the immediately preceding flitch, very little time is required for adjustment of the positions of the edger saw blades by the servo motors160as directed by the control computer74as shown inFIG. 15. There is then only a minimum delay (step18) required between the tail end162of a preceding flitch and the leading end41of the flitch24about to be lowered onto the edger infeed sharpchain124. When the flitch24is to be sawn into boards of different widths and locations on the flitch24than how the preceding flitch has been sawn, the positions of the edger saw blades31must be adjusted along the edger saw arbor158using servo motors164controlled by the control computer, as shown inFIG. 15. This requires additional time (and resulting distance along the edger feed chain124) between the tail end162of the preceding flitch and the leading end41of the flitch24, That distance may be determined by the photocell152sensing passage by the tail end162of the preceding flitch past the #1 tipple134(step14), and by data from encoders on the feed roller121of the edger20. The edger saws31can be quickly relocated on the arbor158as controlled by the computer74, using data from the optimizer76and processed through programmable logic controller77. The edger20can thus be quickly adjusted to saw the flitches172and174into different widths of boards176,178,180and182, shown inFIGS. 16 and 17.

As may be seen inFIG. 12andFIG. 13, rotating the tipples134downward accelerates the flitch in the direction of movement of the upper surfaces of the sharpchain124toward the entry into the space between the press rollers121of the edger itself, as well as lowering the flitch into contact with the top of the sharpchain124.

As the tipples134are rotated downward the infeed press rollers140are also moved downward, remaining in contact with the top face of the flitch124and pressing the flitch first against the outer margins138of the tipples and then against the upper edges of the sharpchain. The sharpchain124then carries the flitch toward the edger20, feeding the leading end of the flitch between the edger press rolls121which then engage the flitch and move it through the saws to cut the flitch into boards according to the optimal sawing solution that was generated by the control computer74prior to operation of the charger mechanism.

After the calculated amount of movement of the tail end162of the previous flitch beyond the tipples, allowing for repositioning of the edger saws as mentioned above, the tipples134are lowered and the flitch24descends down upon the edger infeed sharpchain124and is pressed downward against the edger infeed sharpchain124by the infeed press rollers140. The edger infeed sharpchain124then carries the flitch24toward the edger20. Referring now toFIGS. 14-17the feed rollers121of the edger20then carry the flitch24into engagement by the saws31, which cut the flitch24into boards and scrap edge material according to the sawing solution determined by the control computer74.

By the time the flitch24has been moved far enough into the edger20and is being moved through the saws31by the feed rolls121of the edger20far enough so that the tail end of the flitch24has moved beyond the #1 tipple, the tipple134closest to the edger20, the following flitch26should have been carried by the lower flitch carrier members94and clamp pads120into the edger ready position156, so that the cycle can be repeated as subsequent flitches28,30etc. are moved laterally through the series of hook stops, and are scanned and converted into three-dimensional models and saved in the memory of the control computer74, together with the data necessary to each flitch to the edger ready position and ultimately through the edger20.

Once the preceding flitch has cleared the tipples and the leading end41of the flitch24is supported by the tipples134, when the tipples are lowered the flitch24supported by the tipples is already positioned to be fed to the edger saw blades31in the most advantageous position and orientation. The flitch has only to drop a small distance, such as about 4 inches, from the edger ready position156once the tail end162of the preceding flitch is clear from beneath the leading end41of the flitch24supported by the tipples. Lowering the tipples134, with the edger infeed presser rollers140pushing down on the top of the flitch, accelerates the flitch toward the edger saw blades31, bringing it to a speed approaching that of the edger infeed sharpchain124. The tipples134and the edger infeed presser rollers140continue to positively grasp and hold the flitch24until the flitch-contacting surfaces138of the tipples134have been lowered beneath the level of the upper faces of the edger infeed sharpchain124. The edger infeed sharpchain124then engages and moves the flitch toward the edger press rollers121. This transfer of the flitch24from the infeed scanner and carriage assembly32to the edger infeed sharpchain124and the change of direction from lateral movement to longitudinal movement of the flitch can all occur within a very brief time, as shown inFIG. 20, since the flitches moving laterally are at a higher location than the flitches moving longitudinally and have a shorter travel distance, and thus, the flitches moving laterally can be moved precisely, controlled by the charger sets to a properly oriented edger ready position156directly above the edger feed mechanism22that is moving longitudinally toward the edger saw blades, and the flitch24then can be lowered onto the edger infeed sharpchain.

Each time division on the time axis inFIG. 20represents 100 ms. As may be seen inFIG. 20, an entire cycle184of moving a scanned flitch24from the transfer ready position78, through the edger ready position156, and into the press rollers121of the edger20, occurs in a very short time. The numbered steps shown inFIG. 20are listed in the following table:

During the entire cycle184a flitch transfer charging cycle186, the complete set of actions for transfer of a flitch in a lateral direction from the scanner and carriage assembly32to the charger ready position156, may be completed in less than one second. After necessary delay while a preceding flitch clears the edger infeed mechanism22and enough space is left behind the tail end162of the preceding flitch for the preceding flitch to be clear of the saws31of the edger20and the saw blade positions are adjusted, before the next flitch engages the saw blades31. In a complete sharpchain loading cycle188each flitch can be lowered from the edger ready position156onto the edger feed sharpchain124and delivered into the edger20far enough to be engaged by the second feed press rollers121in slightly more than 0.6 second.