Abstract:
An apparatus for cutting and sorting boards conveys the boards ag a conveyor path. The apparatus senses the length of boards and the grade of boards, and cuts selected boards into first and second segments. The first and second segments are aligned against lumber lines respectively on each side of a conveyor path. The boards are then selectively sorted and dropped into bins successively positioned along each side of the conveyor path.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]    This application is a divisional application of prior U.S. patent application Ser. No. 10/108,216 filed Mar. 26, 2002, the benefit of the priority of which is hereby claimed under 35 U.S.C. §120. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates to cutting and sorting of boards in a sawmill and planermill operation and, more particularly, to an automated system for cutting, trimming, and sorting boards into a plurality of receiving bins in an efficient manner.  
         BACKGROUND OF THE INVENTION  
         [0003]    After rough sawn boards are produced in a sawmill, they are commonly run through a plurality of planing, grading, trimming, cutting, and sorting operations. In current cutting, trimming, sorting operations, a plurality of boards of various lengths, up to 20 ft. long, for example, are fed by a conveyor along a predetermined path in a machine direction. The boards are oriented orthogonally to the machine direction. The conveyor has lugs that advance the board through a sensing station. At the sensing station, shape properties of the board are determined, including length, width, wane (missing wood due to circular shape of the tree), crook and bow. These shape parameters are evaluated along the length of each board to determine the grade of various portions of the board. The board advances in front of a human operator who will make visual based grade decisions based on quality parameters that cannot be determined by the sensing station. The information from the sensing station and the human operator are sent to a programmable logic controller, where the data is analyzed to determine the optimal grade and length solution for the individual board. The programmable logic controller controls a plurality of saws that are spaced laterally across the conveyor at a sawing station. Depending upon the length and grade information, the board can either pass under the saws without being cut, or it can be cut at a predetermined location along the length of the board, depending upon the information received by the programmable logic controller from the sensing station and from the human operator.  
           [0004]    After boards pass the sawing station, the boards pass over a plurality of aligning rollers. These rollers are oriented parallel to the machine direction and rotated in a clockwise direction looking in the machine direction. As the boards pass over these rollers, they are moved to the right looking in the machine direction, until their ends abut a rail running parallel to the right-hand side of the conveyor, normally referred to as a lumber line. If a board has been split in two segments, the programmable logic controller will leave an extra space on the conveyor so that the second segments of the board, which occupied one space on the conveyor when being cut, is now indexed so that it occupies a successive location on the conveyor. The second segments of the cut boards are also aligned against the right-hand lumber line.  
           [0005]    Downstream from the aligning rollers lie a plurality of receiving bins. The receiving bins are positioned under the conveyor in a conventional manner. The programmable logic controller operates drop gates on the conveyor so that boards of common length and grade are dropped into predetermined bins. In this manner, a single bin receives boards of a single length and grade. The bins are periodically emptied and the boards subsequently stacked for shipment in a conventional manner.  
           [0006]    Because each of the boards, whether a single uncut board or a board that has been cut in two, occupy one station on the conveyor downstream of the saws, the actual throughput of the cutter trimmer is reduced by the number of boards that are cut in two because the second segment must also be indexed against the right-hand lumber line. For example, if 10% of the boards are cut in two, then the actual throughput from the machine is reduced by 10%, relative to the number of boards that can be fed into the machine. It is therefore desirable to provide a method and apparatus for increasing the efficiency of the cutter-sorter of the type just described.  
         SUMMARY OF THE INVENTION  
         [0007]    The present invention therefore provides an apparatus for cutting and sorting boards into variable lengths. A conveyor is provided to convey boards along a predetermined path in a machine direction. A sensor is positioned along the path for determining the shape parameters of the board, including length, width, wane, crook and bow. These shape parameters are evaluated along the length of each board to determine the grade of various portions of the board. The board advances in front of a human operator who will make visual-based grade decisions based on quality parameters that cannot be determined by the sensing station. The information from the sensing station and the human operator are sent to a programmable logic controller, where the data is analyzed to determine the optimal grade and length solution for the individual board. A programmable logic controller receives the length and grade signals and determines whether, and at what location along the length of the board, it will be cut into two segments. A saw is positioned along the path downstream from the sensor. The saw is controlled by the controller for cutting the board at the cutting location. Downstream of the saw, a first lumber line is provided adjacent the right side of the path and a second lumber line is provided adjacent the left side of the path. A first lateral conveyor is provided for moving boards laterally toward the right side of the path so that the right ends of the boards adjacent the right side of the conveyor abut and are aligned with the first lumber line. A second lateral conveyor is provided for moving boards laterally toward the left side of the path so that the left ends of the boards adjacent the left side of the conveyor abut and are aligned with the second lumber line. Thereafter, a first plurality of bins are successively positioned under the right side of the conveyor path for selectively receiving boards of predetermined length and grade aligned against the first lumber line. A second plurality of bins are successively positioned adjacent the left side of the conveyor path for selectively receiving boards of predetermined length and grade that are aligned with the second lumber line.  
           [0008]    A method of sawing and trimming boards comprises a plurality of steps including (a) feeding a plurality of boards past a sensing station on a conveyor; (b) sensing the length (and optionally the grade) of each board; (c) determining whether and at what location the board will be sawn; (d) sawing the board at the location; (e) aligning boards adjacent one side of said conveyor against a lumber line on that one side; (f) aligning boards adjacent the other side of said conveyor against a lumber line on that other side; (g) selectively placing boards adjacent the lumber line on the one side into a plurality of bins successively positioned adjacent the one side; and (h) selectively placing boards adjacent said other side in a plurality of bins successively positioned adjacent the other side. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:  
         [0010]    [0010]FIG. 1 is a schematic plan view of a cutter sorter constructed in accordance with the present invention;  
         [0011]    [0011]FIG. 2 is a schematic elevation view corresponding to FIG. 1;  
         [0012]    [0012]FIG. 3 is an enlarged plan view of a portion of a lateral conveyor and the positioning skids associated therewith; and  
         [0013]    [0013]FIG. 4 is an enlarged elevation view of FIG. 3. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0014]    Referring now to FIGS. 1 and 2, the cutter sorter  10  includes a conveyor  12  comprising a plurality of conveyor chains  12   a - 12   k  that are aligned in parallel runs. Only the upper portion of the runs are shown in FIGS. 1 and 2 for simplicity. The conveyor moves in a machine direction indicated by arrows  14 . Each of the conveyor&#39;s chains  12   a - 12   k  carry upstanding lugs  16   a - 16   k . The lugs  16   a - 16   k  are aligned laterally across the conveyor chains  12   a - 12   k  and are positioned at successive locations along the length of the conveyor chains  12   a - 12   k . Each of the sets of lugs  16   a - 16   k  are spaced by the distance slightly greater than the width of the boards to be handled by the conveyor.  
         [0015]    Boards, for example, board  18 , are positioned on the conveyor  12  and are moved in the machine direction  14  via the conveyor chains  12   a - 12   k  and lugs  16   a - 16   k . The boards may have various lengths ranging, for example, from 8 ft. to 20 ft. although, these lengths will depend upon the lumber produced by the sawmill, the trimming operations and the demands of the marketplace for various lengths of boards. The conveyor  12  moves each board past a sensing station where an optical sensor  20  scans the board and generates a signal indicative of the overall length of the board. Alternatively, the board may be scanned in the longitudinal direction prior to being placed on the conveyor. The optical sensor may also be employed to scan the shape of the boards and generate a signal indicative of the grade of the board, for example, whether the board has varying amounts of wane at various locations along the length of the board. In addition to the optical sensor, the board is graded by a human operator for visual defects the optical sensor cannot detect.  
         [0016]    The sensing station provides a length and grading signal to a programmable logic controller  21 . The programmable logic controller  21  also receives input from a human operator as to the most preferred lengths and grades of boards to be produced at a given time by the cutter sorter  10 . This information is then processed by the programmable logic controller  21  to determine whether and at what location along its length a given board will be sawn. The boards are then conveyed to a sawing station. For example, board  22  is positioned under a plurality of rotary saws  24   a - 24   j  at the sawing station. The saws  24   a - 24   j  are positioned at laterally spaced locations along the conveyor  12  between each of the successive chains  12   a - 12   k . The saws  24   a - 24   j  are mounted so as to be vertically moveable into and out of the path of the board  22  as it traverses under the saw station. The logic controller  21  sends a predetermined signal to the saw controller  26 , providing information to lower the appropriate saw and cut board  22  at a predetermined location along its length. As shown in FIGS. 1 and 2, saw  24   f  has been lowered by the saw controller  26  so as to cut the board  22  into two equal lengths. The same operation has already been performed on board  30  downstream of the sawing station.  
         [0017]    Stationary rails, commonly referred to as lumber lines, are provided along each side of the conveyor. The right-hand lumber line  32  is positioned longitudinally along the right-hand side of the conveyor  12  looking in the machine direction while a left-hand lumber line  34  extends longitudinally along the left-hand side of the conveyor  12 . The rails are positioned at a level slightly above the upper surface of the conveyor  12 . The lumber lines  32  and  34  are only shown in FIG. 1 and are omitted from FIG. 2 for simplicity.  
         [0018]    Downstream from the sawing station, a plurality of aligning conveyor rollers  40  have their axes aligned parallel to the machine direction  14  and are positioned between successive runs of the conveyor chains  12   a - 12   k . The upper surface of the rollers  40 , as shown in FIGS. 3 and 4, are positioned slightly above the upper surface of the conveyor chains  12   a - 12   k . The rollers  40  are mounted for rotation by conventional means not shown, to rotate in a clockwise direction looking in the machine direction  14 . As successive boards, for example boards  44   a  and  46   a , pass over the aligning rollers  40 , they will be moved laterally in a right-hand direction as indicated by arrow  50 . The boards  44   a  and  46   a  will be moved laterally until the right-hand ends of the boards  44   a  and  46   a  abut the rail comprising the right-hand lumber line  32 .  
         [0019]    Referring to FIGS. 3 and 4, the left-hand board segments  44   b  and  46   b , corresponding to right-hand segments  44   a  and  46   b , are shown being held in a position above the rollers  40  by a plurality of positioning skids  52  as they pass over aligning rollers  40 . The positioning skids  52  are positioned in a conventional manner between the left hand portion of rollers  40 . The positioning skids are mounted by conventional means for movement in a vertical direction in response to signals from the positioning skid controller  54 , at the appropriate time. For example, as boards  44   a  and  4   b  are being moved to the right by aligning rollers  40 , positioning skids are raised by the controller  54  so as to raise segments  44   b  and  46   b  above the rollers  40 . Thus board segments  44   b  and  46   b  remain laterally stationary as they traverse over the right-hand aligning rollers  40 . When, for example, a longer board, such as board  58 , traversed the right-hand aligning rollers  40 , the positioning skids  52  are lowered to the position shown in phantom in FIG. 4 as board  58  passed over the positioning skids so all of the rollers  40  could have effectively functioned to move the board  58  laterally against the right-hand lumber line  32 .  
         [0020]    A second set of aligning rollers  60  are positioned downstream from the right-hand aligning rollers  40  between the runs of chains  12   a - 12   e  and adjacent the left-hand side of the conveyor  12 . Aligning rollers  60  are rotated in a counterclockwise direction looking in the machine direction  14 . As boards, for example, board segments  62   b  and  64   b , pass over the rollers  60 , they will be moved laterally in a left-hand direction as indicated by arrow  68  toward left-hand lumber line  34  until their left ends abut against the left-hand lumber line  34 . Thus, the left-hand segments of boards  62   b  and  64   b  are aligned to the left-hand lumber line  34  so that they can be sorted separately from the right-hand portions of the boards  62   a  and  64   a . Positioning skids  66  are positioned between the aligning rollers  60 . The skids  66  are in the downward position (corresponding to the position of skid  52  shown in FIG. 4 for the right-hand aligning skids) when boards pass thereover to be aligned to the left-hand lumber line  34 . However, as board  58 , for example, passes over the left-hand aligning rollers  60 , the positioning skids  66  will be raised so that the left-hand aligning rollers  60  will not contact the board  58  and move it away from its alignment with the right-hand lumber line  32 .  
         [0021]    A plurality of right-hand lumber bins  80 ,  82 ,  84 ,  86 ,  88 ,  90 , and  92  are positioned below the upper run of the conveyor  12  and have their right-hand ends aligned with the right-hand lumber line  32 . These bins  80 - 92  are shown for purposes of illustration as corresponding to lumber lengths of 8 ft. to 20 ft., respectively. Fewer or more bins may be employed, as needed or desired. Also, if four grades of wood are being sorted, each of the bins  80 - 92  would have three corresponding partners for receiving the other three grades of boards of the same length. For example, there might be four bins for 8 ft. lengths of lumber, one for the highest grade of lumber, one for the second grade of lumber, another for the third grade of lumber, and a fourth bin containing the lowest lumber grade. For purposes of simplicity in illustration, however, only one bin has been shown for each length of wood. These bins  80 - 92  are for receiving the various lengths of lumber aligned with the right-hand lumber line  32 . A drop gate controller  70  of conventional design receives control signals from the logic controller  21  and controls drop gates  72  on each of the conveyor chains  12   a - 12   k  so as to drop 8 ft. lengths of lumber, for example, into bin  80  and 14 ft. lengths of lumber into bin  86 . The drop gates on the right-hand side are of conventional design but are modified to drop boards only into the right-hand bins  80  to  92 .  
         [0022]    Positioned adjacent the left-hand side of the conveyor  12  are additional bins  100 ,  102 , and  104 . These bins  100 ,  102 , and  104  have their left ends aligned with the left-hand lumber line  34  and are positioned to receive various lengths of lumber aligned with the left-hand lumber line  34 . For example, in the illustration, bin  100  is sized to receive 12 ft. lengths of lumber, bin  102 , 10 ft. lengths, and bin  104 , 8 ft. lengths. Similarly to bins  80 - 92 , bins  100 - 104  may have counterparts for receiving the different grades of lumber as desired. Drop gates (not shown) controlled by drop gate controller  70  drop the lumber into bins  100  to  104  based on control signals transmitted from the logic controller  21  to the drop gate controller  70 . The drop gates on the left-hand side are of conventional design, but modified only to drop boards into the left-hand bins  100  to  104 .  
         [0023]    By adding the left-hand lumber line  34 , aligning rolls  60  with positioning skids  52  and  66 , and bins  100  to  104 , the need to index and align left-hand board segments to the right-hand lumber line is eliminated. In this manner, the machine throughput can be maximized to at or near 100% of the theoretical maximum. In large sawmills, this efficiency increase can result in savings on the order of several million dollars per year.  
         [0024]    While the preferred embodiment of the invention has been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.