Abstract:
A method and apparatus are provided for processing rough cut lumber to convert the rough cut lumber into trimmed to length and dimensionally trimmed to form a standard piece of dimensioned lumber. The process and apparatus includes the formation of a plurality of columns of lumber pieces in addition to a one column operation mode. The lumber pieces in each of the columns are graded, indexed, measured for a trim to length, trimmed to length and then sorted by grade and trimmed length.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     So called dimension lumber is a common commodity. Dimension lumber is formed by cutting lumber pieces from a log to rough cut dimensions and then removing final stock to reduce the lumber pieces to standard cross-sectional dimensions. The dimensioned lumber stock is then typically cut to one of many standard lengths, for example, stud length, 8 foot, 10 foot, 12 foot, etc. to form finished lumber pieces. The final stock removal from the main longitudinal surfaces is typically done by a planer which involves the use of rotary cutting heads as is well known in the art. Rough cut lumber is supplied to a board finishing line that reduces the rough cut transverse dimensions to the final transverse dimensions, and then through a series of steps to a length cutting apparatus that cuts the semi-finished lumber pieces to length to form finished lumber pieces. Various processing stations are involved in the production line and are connected by conveyor systems.  
         [0002]     To be efficient, such processing lines run the lumber pieces through at high speeds and through-put rates. The lumber pieces are slowed down from their high speeds through the stock removal step, particularly prior to reaching the grader, for grading and subsequent length trimming and sorting. Lumber is graded into various grades which grades may be relatively arbitrary or subjective or by a recognized standard. For example, five grades of wood may be provided wherein the grades are determined by the quality of the wood, e.g., the number of knots, the surface finish, grain, etc. One grade of wood is referred to as construction grade. Much dimension lumber is used in construction and has standard cross-sectional dimensions, for example so-called 2×4&#39;s, 2×6&#39;s, etc. Dimension lumber comes in standard lengths, for example, stud length, 8 foot, 10 foot, 12 foot, 14 foot, etc., up to and even sometimes exceeding 24 feet in length. Some lines are built to handle boards 30 feet and even longer. Longer lengths may be provided by joining multiple pieces of short dimension lumber together, for example, with glued finger joints.  
         [0003]     In some processes, the cross-sectional dimensioning of the lumber pieces is done at very high movement speeds, for example, up to 4000 feet per minute through a stock removal device such as a planer. The dimensioned pieces are then removed from the stock removal device, and transferred to downstream processing equipment, but are first preferably slowed down prior to subsequent processing steps, particularly for grading at a grader station. Typically, a lumber processing line is simultaneously handling a large variety of lumber piece lengths, e.g., up to 24 feet, even though the largest quantity may be in the 8-14 foot length grouping. The grader station needs to be wide enough to accommodate the longest anticipated pieces even though much of the width is not needed all the time leading to operational inefficiency. Other downstream equipment must be equally wide to also handle the longest anticipated lumber pieces. Grading may be done manually by people and/or computer (or machine) vision techniques. The lumber pieces are then configured relative to one another prior to reaching a length trimming apparatus for subsequent trimming to length. The lumber pieces are trimmed to length preferably after the cross-section is dimensioned. One or both ends of a lumber piece may be cut in the length trimming station to obtain the desired length. When the processing system produces various trimmed lengths, e.g., 8, 10, 12 and 14-foot lengths concurrently, the trimmed length lumber pieces are then sorted by length and grade, bundled, bound, and then shipped.  
         [0004]     Such lumber processing operations are well known.  
         [0005]     However, even though such processing lines are effective, they do have some drawbacks. A particular drawback is that one or more portions of the processing apparatus present bottlenecks to through-put rates of processed lumber pieces. Operational inefficiencies are also encountered because much of the machine is frequently not being used but needs to be available to handle the longer lumber pieces. One significant bottleneck is the grader, particularly when the grader utilizes manual labor to effect grading. In manual grading, people may turn the boards, inspect all four sides (major longitudinal surfaces) and manually mark grade and trimming instruction designations on the board which are then subsequently read by machine vision with each piece of graded lumber&#39;s location within the processing system being known, along with its final cut to length. This information facilitates the sorting of the boards after trimming to length by both length and grade. While more people may be used to help speed up grading, there is a limited amount of space at a typical grading station, thereby placing an upper limit on the grading through-put rate. Grading stations are typically designed to simultaneously accommodate a full range of board lengths. To facilitate grading, the boards are aligned along one side of the machine, since, e.g., an 8-foot long board on a 24-foot wide grading station cannot be accessed except on one side of the grading station.  
         [0006]     Lumber processing lines are expensive to purchase, to replace and/or modify. They also have an established footprint in a plant which footprint would also be difficult and expensive to change.  
         [0007]     Therefore, there is a need to improve the processing of dimension lumber by improving the through-put rate of lumber pieces particularly at the grading station without requiring major changes in the existing equipment or the footprint occupied by the existing equipment to reduce capital expenditure to solve the problem and to allow simple retrofitting of existing lines.  
       SUMMARY OF THE INVENTION  
       [0008]     The present invention involves the provision of an apparatus for finishing rough cut lumber pieces to form dimensioned lumber. The apparatus can include a stock removal device operable for removing stock from at least one major surface of a piece of rough cut lumber and preferably four major longitudinal surfaces. A first conveyor system is positioned to receive lumber pieces from the stock removal device and transfer them to downstream processing systems. An orienting device is provided that is associated with the first conveyor system and has opposite first and second flow paths or sides. The first side is aligned with a first discharge portion of the first conveyor system to receive a first stream of lumber pieces, and the second side is aligned with a second discharge portion of the first conveyor system to receive a second stream of lumber pieces from the first conveyor system. A length trimming apparatus is provided to cut each lumber piece to a predetermined length if cutting is needed. A sorter is provided downstream of the trimming device and is operable to receive trimmed dimensioned lumber pieces and sort the received trimmed lumber pieces by length and also preferably grade. The apparatus can use existing processing line components and by the addition of a new first conveyor system, permit inexpensive retrofitting to improve apparatus through-put rate.  
         [0009]     The present invention also involves the provision of a method of processing lumber pieces of different lengths, the method can include removing stock from a plurality of lumber pieces to provide the desired transverse dimensions to produce dimensioned lumber pieces. The lumber pieces are discharged in a plurality of streams of lumber pieces with there being at least a first stream and a second stream. The lumber pieces in each stream are indexed and referenced by machine location prior to feeding to a length trimmer. The lumber pieces are fed in at least two streams or columns to the length trimmer. The lumber pieces are trimmed to length, if needed, in the trimmer, with the lengths being predetermined lengths from a respective reference for each of the first and second sides of the trimmer. The trimmed lumber pieces are transferred to a sorter and then sorted by length and preferably grade. The thus sorted lumber pieces are bundled by length and preferably also grade. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is a schematic fragmentary top plan view of an apparatus for processing lumber pieces to produce dimensioned lumber pieces.  
         [0011]      FIG. 2  are fragmentary plan views showing a first portion of the wood processing system of  FIG. 1  showing details of a feed conveyor to the grader with the two views showing a diverter in different positions.  
         [0012]      FIG. 3  is a fragmentary end elevation view of the apparatus of  FIG. 1 .  
         [0013]      FIG. 4  is a fragmentary plan view of a grading station portion of the apparatus of  FIG. 1 .  
         [0014]      FIG. 5  is a fragmentary side elevation view of the portion of the apparatus portions as shown in  FIG. 4 .  
         [0015]      FIG. 6  is a fragmentary top plan view of a dealer portion of the processing line shown in  FIG. 1 .  
         [0016]      FIG. 7  is a fragmentary side elevation view of the apparatus portion shown in  FIG. 6 . 
     
    
       [0017]     Like numbers throughout the various Figures designate like or similar parts and/or construction.  
       DETAILED DESCRIPTION  
       [0018]     The reference numeral  1  designates generally an apparatus operable for converting sawn or rough cut lumber pieces into dimensioned lumber pieces  2 . Dimension lumber is typically considered to be standardized lumber. For example, a 2×4 or 2×6 of various lengths with the cross sectional shape and dimensions being relatively standard. By way of example, a 2×4 has actual dimensions of roughly 1½ inches by 3½ inches. The apparatus  1  includes a first stock removal station designated generally  3  that is operable for removing stock preferably from the four major longitudinal faces of a lumber piece  2 , to reduce the cross-sectional size of the lumber piece to the desired stock dimensions and preferably to smooth the trimmed faces. The conveyor system  5  conveys the trimmed lumber pieces  2  from the trim station  3  to a downstream series of processing stations designated generally  7  that preferably includes a grader station  8 , a dealer station  9 , a transfer apparatus  10 , a length trimming station  11  which cuts the dimensioned lumber pieces to desired lengths, another transfer station  12  that takes length trimmed dimension lumber pieces from the length trimmer  11  and transfers the lumber pieces  2  to a suitable sorter  14 . The sorter  14  is operable to sort the dimensioned and length trimmed lumber pieces by length and preferably grade.  
         [0019]     The apparatus  1  includes an in-feed conveyor  16  that conveys rough cut lumber pieces  2  to the stock removal station  3 . The station  3  can be any suitable device that is operable to remove (trim) stock from one or more of the major longitudinal surfaces of the rough cut lumber pieces and preferably all four of the major surfaces. The station  3  can include any suitable device for removing stock from the rough cut lumber and in a preferred embodiment, the station  3  includes a plurality of rotating planer heads with each head adapted to engage a respective surface of the rough cut lumber pieces. The rotating heads are well known in the art and can rotate at very high speeds (angular velocity) to allow high speed through-put of the rough cut lumber pieces  2 . Such planers are well known in the art. Although a planer can be used to trim the major longitudinal surfaces, other stock removal devices can be used so long as they leave the appropriate surface finish on the surfaces of the board or can be followed by a device to provide desired surface finish and not “burn” or blemish the wood as it is cut. For example, a circular saw blade can also be used if it can produce the desired surface finish at the desired speed. The station  3  has devices to align the lumber pieces  2  in relationship to the cutting devices. In high speed operation, the lumber pieces can move up to about 4,000 feet per minute as they exit the station  3 . Some lumber pieces  2  may be processed as rough cut eliminating the need to trim the major surfaces but still need to be graded, cut to length and sorted. The trim station  3  may thus be eliminated or bypassed in this event.  
         [0020]     At the output side of the trim station  3  or another feed device (not shown), a conveyor system  5  is provided. The conveyor system  5  is operable to receive cross sectionally dimensioned lumber pieces  2  from the station  3  and convey the lumber pieces to downstream processing equipment. The conveying system  5  includes at least two conveyor runs  18 ,  19  which are shown as being positioned in side-by-side relationships and preferably being generally coplanar at least from the station  3  to a directing device  20 . The runs  18 ,  19  could also be arranged in superposed relationship. Each run  18 ,  19  may comprise its own sets of conveyor belts or the like, and are operable to provide at least two flowstreams or columns of dimension lumber pieces  2  from the trim station  3  as described below. A directing device  20  such as a gate diverter may be provided adjacent the upstream ends of the runs  18 ,  19  to shift each discharged lumber piece  2  to a desired conveyor run  18  or  19 . In a preferred embodiment, alternating pieces of lumber  2  from the station  3  are fed down the runs  18  and  19  to provide an equal or substantially equal number of lumber pieces  2  to each of opposite sides of a grader  8  as described below or alternately, selectively to one side only of the grader. The runs  18  and  19  are similar in construction and preferably each is provided with at least one slowdown device and preferably a plurality of slowdown devices  21 ,  22 . The slowdown devices  21 ,  22  may be diagonally directed conveyor belts which receive thereon a dimensioned piece of lumber  2  from the respective run  18 ,  19  or an upstream slowdown device to reduce the forward speed of the lumber piece  2  and then feed it to the downstream slow down device  22  for subsequent transfer to a respective landing table  23 ,  24  of the grader  8 . As an example, the lumber pieces  2  from a conveyor  18 ,  19  will be slowed down by the first slowdown device  21  from high speed to medium speed and then slowed down by the second slowdown device  22 , to slow speed and then be slowed down more upon transfer to the landing table  23  and then move generally transversely to the direction of travel along the conveyor system  5 . The lumber pieces  2  from each of the runs  18 ,  19  are discharged onto a respective landing table  23 ,  24  and are then transferred to the grader  8  to move in a direction generally normal to the direction of movement of the lumber pieces  2  along the runs  18 ,  19  selectively in one or more columns. The apparatus  1  may be operated in a single run mode or a plurality of runs mode. In a single run mode, either the run  18  or  19  is utilized to feed lumber pieces to the grader  8  and in a plurality of runs mode, the runs  18 ,  19  both feed lumber pieces  2  to the grader  8  landing tables  23 ,  24 . While the illustrated apparatus  1  is constructed for up to two columns in the grader  8 , it may be constructed for more than two columns by adding more landing tables  23 ,  24  and more runs  18 ,  19 . A lumber processing apparatus  1  may be made by retrofitting an existing apparatus with the conveyor system  5  to provide for selective two side operation.  
         [0021]     In the illustrated structure, the dimensioned lumber pieces  2  exiting the run  18  are fed to a first side  27  of the grader  8  while the dimensioned lumber pieces  2  from the run  19  are fed to a second side  28  of the grader  8 . As seen in  FIGS. 1, 3 , the landing table portion  23  is provided and is positioned in overlying relationship to the conveying system  33  such as parallel chains  31 , which is part of the grader  8 . The grader  8  orients the received lumber pieces  2  into an appropriate number of streams or columns A, B, e.g., one or two (or more if desired), and also generally aligns one end of each lumber piece  2  in each formed column preferably to an outer machine edge of the conveyor system  25 . The lumber pieces  2  are positioned both transversely of the grader  8  and longitudinally of the grader  8 . Lumber pieces  2  from the run  19  are fed to the landing table  24  and are discharged onto the conveyor system  33  on the side  28 . The use of a slow down device the run  19  may be eliminated since a mechanical fixed stop may be used to configure the lumber pieces  2  on the side  28  as can friction between the lumber pieces and the landing table portion  24 . Indexing rollers  35  receive lumber pieces  2  from the landing table  24  and by rotating clockwise as seen in  FIG. 3 , will move the outward end  34  of a lumber piece  2  against a stop  36  to transversely position the lumber piece  2  for downstream processing. The landing tables  23 ,  24  are provided with a conveyor system  25  to move the dimensioned lumber pieces generally at a right angle to the direction of movement from the runs  18 ,  19  for subsequent discharge onto the conveyor chains  31 . Rollers  38  are provided for transversely positioning the lumber pieces  2  on the landing table  23  to the inside  27  for transverse alignment or registration on the grader  8 . The rollers  38  are provided for receiving dimensioned lumber pieces  2  from the run  18  and landing table  23  and as seen in  FIG. 3 , would rotate counterclockwise and move received lumber pieces  2  to the side  27  to abut a stop  42  for transverse alignment or registration. The conveying system  33  can include a plurality of conveyor devices such as the chains  31  to advance the thus received dimensioned lumber pieces  2  from the landing tables  23 ,  24  forward through the grader  8 . In the event the apparatus  1  is used in a single side or column grader mode, the rollers  38  could be used to move all received dimensioned lumber to the side  27 . Alternatively, the rollers  35  could also be rotated counterclockwise (reversed) for single side operation.  
         [0022]     In dual line use, the chains  31  advance the dimensioned lumber pieces  2  in two columns positionally indexed at outside ends through the grader  8  at stops  36 ,  42 . In the grader  8 , the lumber pieces  2  are preferably inspected either manually by people, or by machine vision to determine the grade and trim criteria of each of the dimensioned lumber pieces  2  and provide a cut to length. In a preferred embodiment, the lumber pieces  2  are marked with a marking that is machine readable to indicate the grade and preferably trim coding. Trim coding can be used to provide instructions to the trim station  11  what parts of a lumber piece need to be removed, e.g., a knotty portion to improve grade. Manual grading of the lumber pieces  2  may involve turning of the pieces to view each of the major longitudinal surfaces. After passing through the grader  8 , the dimensioned and graded lumber pieces  2 , which are oriented generally transversely to the direction of travel, are fed through a device, referred to as a dealer  9 . Sensors, such as microswitches or optical sensors can be used to provide overall length information about a lumber piece  2  to the trim station  11  which information is preferably coordinated with the trim coding as is known in the art.  
         [0023]     The dealer  9  preferably accomplishes at least two functions. The first function is to separate (space apart) and sequence the lumber pieces  2  and second, indexes the location of each individual lumber piece  2  on downstream conveyors such as conveyor  10 . A signal is provided to a computer system  45  to indicate the trim length, grade and position of each individual lumber piece  2 . The transfer conveyor  10  maintains the machine location of each individual lumber piece  2  which positions are known by a computer system  45 , e.g., a PLC that stores information regarding each lumber piece  2  location, its estimated actual length and will compute a trim to length for each lumber piece  2  at each machine location. An acceptable computer system  45  includes a ControlLogix PLC, PanelView Plus operator console with PowerFlex series frequency driver by Allen-Bradley. The drives and remote I/O can be controlled over DeviceNet. Readers  41  are provided, for each column of dimensioned lumber pieces  2 . In one column operation, only one reader  41  is needed. To retrofit an existing apparatus for processing a plurality of columns of lumber pieces  2 , additional readers  41  may be added. Each dimensioned lumber piece  2  is preferably marked in the grader  8  by a worker or by machine with a grade designation, trim instructions and its machine location which information is stored in the computer  45 . The actual length may be determined, e.g., by any suitable sensor preferably located adjacent the entrance to the trim station  11  and may be incorporated in the readers  41 , if desired, after the machine location is known. The computer determines a trim to length for each lumber piece  2  which is also stored in the computer  45  and is referenced to the lumber pieces  2  machine location. A particularly effective dealer  9  can include a tong loader which removes lumber pieces  2  from the grader  8  and transfers them to the transfer conveyor  10  with the pieces being fixed in machine location by cleats  49  on the conveyor chains  47 . Rollers  43 ,  44  are provided to ensure that at least one end of each lumber piece  2  is end aligned or registered to assist in the length trimming step. The rollers  43  move the lumber pieces  2  to an outside guiderail  48  while the rollers  44  move lumber pieces in the other column to an inside guide rail  46 . The transfer conveyor  10  then moves the indexed lumber pieces  2  to the trim or cut off station  11 .  
         [0024]     The trim station  11  will have a plurality of transversely spaced cutting devices A-M, e.g., circular saw blades mounted therein selectively movable into engagement with a particular dimensioned lumber piece  2 . The computer  45  provides a signal to a cutting head  49  and indicates which cutting devices A-M are to be moved for engagement with a particular lumber piece  2  as indicated by its trim to length criteria or other trim instructions stored in the computer  45 . Indexing of the lumber pieces  2  by machine location is maintained by the trim station  11  in both columns of lumber pieces  2 . For example, if the computer  45  indicates that a lumber piece  2  is to be trimmed to an 8 foot length, saws A and E may be moved into cutting engagement with the lumber piece  2  while if the computer  45  indicates that the piece is to be a 10 foot piece, saws A and F would be moved into cutting engagement with the lumber piece  2 . The trimmed end or ends or mid portion from each lumber piece  2  is/are then removed for subsequent processing, as for example conversion into chips or the like or as a fuel source. The machine location of each trimmed to length lumber piece  2  is maintained and known by the computer  45  after the cut lumber pieces are transferred by the transfer conveyor  12  to a sorter  14 . The transfer conveyor  12  may be inclined upwardly to elevate the lumber pieces  2  for sorting and depositing by sorter  14 . Tipples, as are known in the art, may be provided at desired locations, e.g., at the dealer  9 , to permit ejecting a lumber piece  2  from the apparatus  1  and possibly reinserting a subjected lumber piece for further processing.  
         [0025]     A preferred sorter  14  is an under conveyor bin sorter that has a plurality of spaced bins  51  positioned under the conveyor  50 . Many types of sorters  14  are well known in the art. When a particular lumber piece  2 , designated by its length and grade, passes to an appropriate bin  51  (one assigned to receive lumber pieces of a particular combination of length and preferably grade), support arms, not shown, move upwardly opening the top of a selected bin  51  wherein the lumber piece  2  is deposited into the bin  51  by gravity. Depositing in a bin  51  continues until an appropriate number of cut pieces, e.g., 208, are contained in the bin  51  as monitored by computer  45  after which the bin contents are emptied for binding in a bundle once a predetermined number of pieces  2  are accumulated. In a hypothetical operation, if there are four lengths and five grades, at least twenty bins  51  would be provided, one for each combination of length and grade. Additional bins  51  however would preferably be provided to provide time for emptying of a bin  51  by providing an alternate bin as controlled by computer  45  for a particular grade and length of lumber pieces. In the event a bin  51  is full, the computer  45  will assign a new bin  51  to receive a particular grade and length of trimmed to length lumber pieces  2 . In other words, a bin  51  over a long period of operation could be used to accumulate and discharge various lengths and grades as set up by the computer  45 .  
         [0026]     The apparatus  1  as described above can be used in two modes, a multiple column mode and a single column mode. In a single column mode, the run  19  and directing device  20  would be deactivated as with a decoupler  61  as would its landing table  24 . All lumber pieces  2  exiting the trim station  3  would be sent down one run, e.g., run  18  and processed by moving in one column down one side of the grader  8  and then would be processed as described above by indexing, trimming to length and sorting. Typically, in a lumber mill, the lumber pieces  2  are being fed through in random lengths but having a relatively uniform cross section. Thus, for a typical processing line, it can accommodate lumber pieces up to 24 feet in length when used in a single column mode. When used in a multiple column mode, both sides of the grader  8  are utilized which allows faster grading because two sides can be used to effect the grading manually or by machine increasing the through-put rate significantly. The decoupler  61  may be operably connected to drive devices for the various conveyers downstream of the landing tables  23 ,  24  and other equipment like the dealer  9  and trim station  11  to selectively operate them in single column or multiple column modes. It has been found, by calculation, an increase in through-put rates of about 50 percent can be accomplished for manual grading. This also allows an increase in the operating speed of the stock removal station  3  allowing the lumber pieces  2  to move through at a faster speed during dimensioning and along the conveyors  18 ,  19  also permitting an increase in through-put rate for the apparatus  1 . In dual column mode, a full length board, for example a 24 foot board is preferably not processed, only shorter lengths of lumber pieces will be processed to achieve manual grading. For example, in a 24 foot wide grading station, lumber pieces up to about 12 feet long, or even longer if desired, could be processed in dual columns. Longitudinal or machine direction staggering of the boards as they pass through the grader  8  though could permit lumber pieces  2  in excess of one half of the width of the grader  8  to be processed.  
         [0027]     To process unfinished lumber pieces  2 , the trimmer  11  may be bypassed or eliminated.  
         [0028]     Thus, there has been shown and described several embodiments of a novel invention. As is evident from the foregoing description, certain aspects of the present invention are not limited by the particular details of the examples illustrated herein, and it is therefore contemplated that other modifications and applications, or equivalents thereof, will occur to those skilled in the art. The terms “having” and “including” and similar terms as used in the foregoing specification are used in the sense of “optional” or “may include” and not as “required”. Many changes, modifications, variations, and other uses and applications of the present construction will, however, become apparent to those skilled in the art after considering the specification and the accompanying drawings.