Abstract:
Provided is a positioning fence for use in lumber sawmills and method of using the positioning fence that facilitates automated positioning of lumber for cutting and a method of positioning lumber for cutting. Also provided is a retrofit position fence table and a method of using the retrofit position fence table. A continuous moving track loop has a plurality of paddles laterally positionable across the width of the track. A track moving device is used to adjust the final locked position of the paddles if the paddles are not locked in the desired position.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to positioning fences for lumber or timber in sawmills or planermills and methods of using the positioning fences. 
       BACKGROUND OF THE INVENTION 
       [0002]    In sawmills, various lumber or timber handling machinery is provided to cut and shape the lumber or timber into saleable wood products. One of the required operations in a mill, after sawing or forming to the desired cross section, is end trimming individual boards or timbers to a specified length. The term “sawmills” includes planermills. 
         [0003]    To cut the material to length, a typical arrangement of transport equipment has a conveyor that has a lug chain table to transport the lumber pieces to length cutting saws. The lumber pieces are carried along the conveyor in equidistantly spaced succession based on the lug spacing of the lug chains. The conveyor has a set of lateral alignment rollers. The lateral alignment rollers form a roller bed system placed at right angles to the lug chain, which operate to urge one end of the lumber material toward a stop or fence, also referred to as a paddle. In this arrangement, each successive piece of lumber is spaced from the other in the direction of travel along the lumber conveyor by the lugs of the lug chain and one of the ends of the lumber is laterally aligned to the stop or fence. 
         [0004]    The piece to be cut to length is positioned for contact with a saw or series of saws. In the configuration of sawmill conveyor equipment just described, the saws are stationary relative to the conveyor and the board is laterally positioned on the conveyor relative to the saw blade. A positioning fence, which one end of the lumber piece abuts against, controls the lateral position of the lumber piece on the feed conveyor. Numerous prior art arrangements for adjustable positioning fences for use with such a feed conveyor arrangement have been proposed in the past. For example a step positioning fence is disclosed in the published Canadian Patent application 2,241,481 of Wight et al. The stepped positioning fence of Wight has a plurality of rigid elevated faces, or steps that extend longitudinally along a side of the fence in an adjacent stepped array of differing offset spacing. The fence is oriented to present one of the steps for contact with the lumber piece to align the lumber end to the corresponding offset of that step. The lumber is urged into contact with the fence by the lateral alignment rollers resulting in alignment of the lumber end to the fence step offset. The stepped fence provides fixed incremental ending settings and a positioning mechanism to ensure the board is presented with a step suitable to obtain the desired or intended lateral translation of the board piece. 
         [0005]    Another flexible trimmer position fence is disclosed in Canadian Patent 2,191,390 to Jackson, which discloses a board positioning fence comprised of a plurality of adjustable fence elements each staged one after the other in the downstream direction of travel of the lumber to be positioned. The lumber is urged against the positioning fence by lateral alignment or ending rollers. The ending rollers urge the lumber laterally across the feed conveyor into contact with the successive fence elements of the board positioning fence. When the desired lateral positioning of the board is achieved, lift skids are engaged to remove the lumber from contact with the lateral urging end rollers. This arrangement has multiple flexible fence elements, which are adjusted to allow the board to be ended to the desired positioning or ending location. Once the board has been displaced laterally to the desired position offset, skids are engaged that lift the positioned lumber piece away from the ending rollers. 
         [0006]    Another arrangement to provide board lumber end positioning is disclosed in the Canadian patent 2,236,508 of Hannebauer et al. Hannebauer discloses a circulating paddle positioning fence with a flexible guide track. Actuators position the flexible guide track, which results in corresponding positioning of a paddle to a desired offset or ending position. 
         [0007]    And yet another positioning mechanism is disclosed in the published Canadian Patent application 2,345,872 of Jobin, for apparatus for positioning pieces of wood for precise cutting. Jobin discloses an adjustable barrier, which is provided with actuators to position the barrier to the desired offset location. Various forms of adjustable barriers are shown including ones which have a face that remains perpendicular to the board as well as providing for incline planes that have a set displacement selected by an actuator to achieve an ending or offset of the lumber laterally to the desired offset amount. 
         [0008]    A further positioning mechanism is disclosed in U.S. Pat. No. 7,419,047. This patent discloses a continuous moving track loop having a plurality of paddles laterally positionable across the width of the track. Complex mechanical brake mechanisms, positioning cams and reset cams are used to position the paddles. 
         [0009]    It is very difficult to accurately position the paddles on the track and often the paddles are not locked at the desired location. There is a need for a device which checks the locked paddle position and adjusts the final locked paddle position. 
       SUMMARY OF THE INVENTION 
       [0010]    An objective of the invention is to provide a device which checks the locked paddle position and then adjusts the locked paddle position by moving the track if the paddle is not locked in the desired position. 
         [0011]    Another objective of the invention is to provide a device in which the paddle is locked in a rough position and the final position of the locked paddle is performed by moving the track if the locked paddle is not in the desired position. 
         [0012]    A further objective of the invention is provide an infinite number positions for the locked paddle. 
         [0013]    Another objective is to provide an apparatus for retrofitting conventional position fences to provide a greater accuracy of the final locked paddle position. 
         [0014]    The invention relates to an apparatus for positioning a lumber piece comprising:
       a continuous track loop having an in-feed end and an out-feed end;   a plurality of paddles spacedly disposed along the length of the continuous track loop, at least one paddle slideably mounted along a bearing way coupled to the track loop so that the paddle is laterally displaceable across a width of the track loop, and wherein the paddle comprises a lumber surface for contacting a surface of the lumber piece and stopping the lumber piece in a desired position perpendicular to a longitudinal direction of the track loop during use;   a paddle locking mechanism constructed to lock the paddle in a desired position on the bearing way;   a paddle moving device constructed to place the paddle in a desired position where the paddle is locked in position on the bearing way by the paddle locking mechanism;   a paddle position sensor constructed to measure the position of the locked paddle;   a track moving device constructed to move at least the out-feed end of the track in a lateral direction; and   a controller connected to the paddle position sensor and track moving device, the controller constructed to compare the measured position of the locked paddle to the desired position of the locked paddle and if the measured position of the locked paddle is other than the desired position the controller is constructed to activate the track moving device to move at least the out-feed end of the track so that the locked paddle is placed in the desired position.       
 
         [0022]    The invention also relates to a method for positioning a lumber piece using an apparatus comprising:
       a continuous track loop having an in-feed end and an out-feed end;   a plurality of paddles spacedly disposed along the length of the continuous track loop, at least one paddle slideably mounted along a bearing way coupled to the track loop so that the paddle is laterally displaceable across a width of the track loop, and wherein the paddle comprises a lumber surface for contacting a surface of the lumber piece and stopping the lumber piece within 5 inches of a desired position perpendicular to a longitudinal direction of the track loop during use;   a paddle locking mechanism constructed to lock the paddle on the bearing way;   a paddle moving device constructed to place the paddle within 5 inches of a desired position where the paddle is locked in position on the bearing way by the paddle locking mechanism;   a paddle position sensor constructed to measure the position of the locked paddle;   a track moving device constructed to move at least the out-feed end of the track in a lateral direction; and   a controller connected to the paddle position sensor and track moving device, the controller constructed to compare the measured position of the locked paddle to the desired position of the locked paddle and if the measured position of the locked paddle is other than the desired position the controller is constructed to activate the track moving device to move at least the out-feed end of the track so that the locked paddle is placed in the desired position, the method comprising;   operating the track;   moving a paddle to a desired position on the bearing way;   locking the paddle in position on the bearing way using the paddle locking mechanism;   measuring the position of the locked paddle using the paddle position sensor;   comparing the position of the locked paddle to the desired position of the paddle using the controller; and   if the position of the locked paddle is different from the desired position, activating the track moving device to move at least the out-feed of the track in a lateral direction and move the locked paddle to the desired position.       
 
         [0036]    The invention further relates to retrofit position fence table comprising:
       a table top sized and constructed to mount a position fence on top of the table top, the table top having an in-feed end and an out-feed end which correspond to an in-feed end and an out-feed end of a position fence when mounted on the table top;   a table base, the table top being mounted to the table base so that at least the out-feed end of the table top is moveable in a lateral direction;   a track moving device constructed to move at least an least the out-feed end of the table top in a lateral direction;   a paddle position sensor constructed to measure a position of a locked paddle when a position fence is mounted on the table top; and   a controller connected to the paddle position sensor and track moving device, the controller constructed to compare the measured position of the locked paddle to the desired position of the locked paddle and if the measured position of the locked paddle is other than the desired position the controller is constructed to activate the track moving device to move at least the out-feed end of the table top so that the locked paddle is placed in the desired position.       
 
         [0042]    The invention also relates to a method for positioning a lumber piece using an apparatus comprising:
       a position fence comprising;
           a continuous track loop having an in-feed end and an out-feed end;   a plurality of paddles spacedly disposed along the length of the continuous track loop, at least one paddle slideably mounted along a bearing way coupled to the track loop so that the paddle is laterally displaceable across a width of the track loop, and wherein the paddle comprises a lumber surface for contacting a surface of the lumber piece and stopping the lumber piece in a desired position perpendicular to a longitudinal direction of the track loop during use;   a paddle locking mechanism constructed to lock the paddle in a desired position on the bearing way; and   a paddle moving device constructed to place the paddle in a desired position where the paddle is locked in position on the bearing way by the paddle locking mechanism; and   
           a retrofit position table comprising:
           a paddle position sensor constructed to measure the position of the locked paddle;   a table top having the position fence mounted thereon, the table top having an in-feed end and an out-feed end which correspond to the in-feed end and the out-feed end of a position fence;   a table base, the table top being mounted to the table base so that at least the out-feed end of the table top is moveable in a lateral direction;   a track moving device constructed to move at least an least the out-feed end of the table top and out-feed end of the track in a lateral direction; and   a controller connected to the paddle position sensor and track moving device, the controller constructed to compare the measured position of the locked paddle to the desired position of the locked paddle and if the measured position of the locked paddle is other than the desired position the controller is constructed to activate the track moving device to move at least the out-feed end of the table top and track so that the locked paddle is placed in the desired position, the method comprising;   
           operating the track;   moving a paddle to a desired position on the bearing way;   locking the paddle in position on the bearing way using the paddle locking mechanism;   measuring the position of the locked paddle using the paddle position sensor;   comparing the position of the locked paddle to the desired position of the paddle using the controller; and   if the position of the locked paddle is different from the desired position, activating the track moving device to move at least the out-feed end of the table top and the out-feed end of the track in a lateral direction and move the locked paddle to the desired position.       
 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0060]      FIG. 1  is a top view of an embodiment of the positioning fence; 
           [0061]      FIG. 2  is a top view of an embodiment of the positioning fence; 
           [0062]      FIG. 3  is a side view of the positioning fence of  FIG. 1 ; 
           [0063]      FIG. 4  is a side view of the positioning fence of  FIG. 2 ; 
           [0064]      FIG. 5  is a side view of an embodiment of the retrofit positioning fence table; 
           [0065]      FIG. 6  is side view of an embodiment of the retrofit positioning fence table; 
           [0066]      FIG. 7  is a side view of a positioning fence mounted on top of a the retrofit positioning fence of  FIG. 6 ; 
           [0067]      FIG. 8  is a top view of the retrofit positioning fence table of  FIG. 5 ; 
           [0068]      FIG. 9  is a top view of the retrofit positioning fence table of  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION 
       [0069]    The inventions will now be explained with reference to the non-limiting Figures. 
         [0070]      FIGS. 1 and 2  show embodiments of the positioning fence of the present invention. Positioning fences are now well known and any positioning fence can be modified according to the present invention. Suitable examples of positioning fences are disclosed in Canadian Patent Application Nos. 2,191,390; 2,236,508; 2,241,481; and 2,345,872; and U.S. Pat. No. 7,419,047, the complete disclosures of which are incorporated herein by reference. A preferred positioning fence is shown in my U.S. patent application Ser. No. 12/781,845, filed 18 May 2010, the complete disclosure of which is incorporated herein by reference. 
         [0071]    The positioning fence is generally depicted by reference numeral  10 . The positioning fence has a continuous loop track  16  extending between an opposed set of end rollers (not shown). The width of the track  16  is generally about 3 feet, but any desired width can be used. The top of the track  16  moves in a left to right direction, as shown by the arrow A. The track  16  includes a plurality of paddles  18  spaced along the continuous track  16  corresponding to the lumber spacing of the individual lumber pieces that the lumber position fence will be used to position. The paddles  18  have a surface  19  for interacting with the lumber pieces  14 . 
         [0072]    At least one of end rollers is driven to cause the track  16  and the paddles  18  to move in a longitudinal direction, that is in the direction of travel of the lumber  14 , which is generally depicted by arrow A. An end roller can be driven by and in time with the lumber conveyor or by a separate drive that follows the movement of the lumber conveyor exactly. At least one of the paddles  18  is mounted for lateral sliding movement across the width of the track loop along a bearing way  20 . The bearing way  20  is oriented for lateral movement of the paddle  18 , which is a direction perpendicular to the longitudinal direction of the track  16 . 
         [0073]    The paddle  18  has a paddle locking mechanism  22  constructed and arranged to lock the lateral position of the at least one paddle. The paddle locking mechanism  22  can comprise any suitable locking mechanism. Preferably, the locking mechanism uses detents and a pin, as described in my U.S. patent application Ser. No. 12/781,845, filed 18 May 2010. Without the claimed invention, the preferred distance between detents was about 0.5 inch apart. However, with the claimed invention, the preferred distance between detents is greater than 1 inch and less than 3 inches, more preferably from 1 to 2 inches. With the present invention, the paddle  18  can be locked at a rough position, usually within 1 inch of the desired position. If the locked position is not the desired position, the present invention moves the locked paddle  18  to the desired position. Furthermore, conventional position fences  10  are limited to locked paddle  18  positions at the detents, while the present invention allows an infinite number of positions for the locked paddle  18 . 
         [0074]    As the detents become closer together, the accuracy of stopping the paddle locking mechanism  22  in the correct detent so that the locked paddle  18  is in the desired location becomes more difficult. Furthermore, if there is no detent at the desired position, the paddle  18  cannot be locked in the desired position. Moreover, when locking mechanisms  22  rely upon other methods to secure the location of the locked paddle  18 , such as by friction, the paddle  18  often is not locked in the desired position. The present invention solves this problem by adding a final adjustment to the paddle  18  after the locking mechanism  22  locks the paddle in position on the bearing way  22 . Thus, the present invention can be used to retrofit existing position fences  10 . 
         [0075]    The present invention incorporates a track moving device  32 , such as a hydraulic, electric or pneumatic actuator, or other motorized device, which moves at least the out-feed end of the track  16  in a lateral direction shown by the arrows B. The track moving device  32  preferably includes a feedback device  33  that confirms the location of the track  16  or the table top  50 . While any feedback device  33  can be used, the feedback device  33  can be for example a transducer or an encoder. Commercial examples of a track moving device  32  having a feedback device  33  includes any of the electric Moog linear motors, disclosed at www.calinear.com. A commercial example of a transducer type of feedback device  33  is the MTS temposonic transducer, disclosed at http://www.acshydraulics.com/temposonic.html. Hydraulic or pneumatic actuators can be used in conjunction with a servo or proportional valve to control the speed and position of the cylinder. The feedback device  33  is connected to the controller  34 . 
         [0076]    In  FIGS. 1 and 3 , the track  16  is mounted on the in-feed end using a pivot  40  and a movable base  42  on the out-feed end. In this manner, when the track moving device  32  is activated, the out-feed end of the track  16  rotates about the pivot  40 , which includes a lateral movement component, and thus the out-feed end of the track  16  moves laterally in either of the directions shown by the arrows B. The movable base  42  can be any as desired, such as wheels or slides. In this embodiment, preferably the movable base  42  uses wheels. For example, the wheels can be flat or mounted on tracks in an arc about the pivot point. 
         [0077]    In  FIGS. 2 and 4 , the track  16  is mounted on a movable base  44  so that both the in-feed and out-feed ends of the track  16  move laterally as shown by the arrows B. The movable base  44  can be any as desired, such as wheels, slides, or bearings. The wheels can be flat, curved, or on tracks, such as a v-track. In this embodiment, preferably the movable base  44  uses slides. The movable base  44  preferably also includes an optional rack-and-pinion  58  so that both ends of the track  16  move at the same time no matter where the track moving device  32  is mounted. The optional rack-and-pinion  58  is described with reference to  FIG. 5  below, with the rack-and-pinion  58  being connected between the track  16  and the floor, such as by a metal plate  52  mounted on the floor. 
         [0078]    Preferably, the track moving device  32  is capable of moving the track  16  at least 0.1 inch in either direction shown by the arrows B, more preferably up to 3 inches, and even more preferably up to 1 inch. In most cases, the track  16  will be moved in either of the lateral directions shown by the arrows B by 0.75 inch or less. 
         [0079]    In the present invention, a paddle position sensor  30 , such as a laser sensor, is located on the out-feed side of the track  16  and is used to determine the actual position of the locked paddle  18 . A programmable computer controller  34  is used to control the operation of the paddles  18  and is connected to the paddle position sensor  30  and track moving device  32 . A commercial example of the programmable computer controller  34  is an A.B. ControLogix 5000 series. However, any suitable controller  34  can be used. With the addition of a paddle position sensor  30  connected to the controller  34 , the exact location of the locked paddle  18  can be determined and compared to the desired position. If the locked paddle  18  is not in the desired position, the controller  34  is constructed to activate the track moving device  32  and move the track  16  in a lateral direction so that the locked paddle  18  is located in the desired position without unlocking the paddle  18 . 
         [0080]    The invention also includes a retrofit position fence table  48  as shown in  FIGS. 5-9 . The retrofit position fence table  48  includes a table top  50  and table base  52 . The table top  50  is sized and constructed to have a position fence  10  mounted thereon, as shown in  FIG. 7 . In this manner, conventional position fences  10  can be easily upgraded to practice the present invention. 
         [0081]    An embodiment of the retrofit position fence table  48  is shown in  FIG. 5 . The table top  50  is mounted on the table bottom  52  by a movable base  44  so that both the in-feed and out-feed ends of the table top  50  move laterally, as shown by the arrows B in  FIG. 9 . The movable base  44  can be any as desired, such as wheels, slides, or bearings. The wheels can be flat, curved, or on tracks, such as a v-track. In this embodiment, preferably the movable base  44  uses slides. The movable base  44  preferably also includes an optional rack-and-pinion  58  so that both ends of the table top  50 , and when the position fence  10  is mounted on the table top  50 , both ends of the track  16  move at the same time no matter where the track moving device  32  is mounted. The rack-and-pinion  58  includes racks  60  mounted to opposite ends of the table top  50 , gears  62  engaged with the racks  60 , and the gears  60  being connected by an equalizer shaft  64 . 
         [0082]    Another embodiment of the retrofit position fence table  48  is shown in  FIG. 6 . The table top  50  is mounted to the table bottom  52  by a pivot  40  on the in-feed end and a movable base  42  on the out-feed end. A track moving device  32  is connected to the table top  50 . In this manner, when the track moving device  32  is activated and a position fence  10  is mounted on the table top  50 , the out-feed end of the table top  50  rotates about the pivot  40 , which includes a lateral movement component, and thus the out-feed end of the table to  50  moves laterally in either of the directions shown by the arrows B, as shown in  FIG. 8 . Thus, when a position fence  10  is mounted on the retrofit position fence table  48 , the out-feed end of the track  16  moves laterally, as shown by the arrows B, when the track moving device  32  is activated. The movable base  42  can be any as desired, such as wheels or slides. In this embodiment, preferably the movable base  42  uses wheels. For example, the wheels can be flat or on tracks mounted in an arc about the pivot point. 
         [0083]    The invention also relates to a method of locating a piece of lumber  14  on a conveyor that is transporting the lumber with one end of the lumber contacting the surface  19  of the paddle  18 . During use, a piece of lumber  14  being transported on the conveyor is urged toward the paddle  18  traveling on track  16 . The paddle  18  prevents further movement of the lumber in a direction perpendicular to the travel of the track  16  when the locking mechanism  22  is switched to a closed position which locks the paddle  18  in place on the bearing way  20 . The paddle position sensor  30  determines the location of the locked paddle  18  and sends the information to the controller  34 . The location of the locked paddle  18  is compared to the desired location and if the location of the locked paddle  18  is not at the desired position, the track moving device  32  is activated to move the track  16  in a lateral direction so that the locked paddle  18  is located in the desired position without unlocking the paddle  18 . The position of the track  16  is confirmed by the feedback device  33 . Once the locked paddle  18  is in the desired position, the lumber  14  urged against the surface  19  of the locked paddle  18  will be in the desired position. The lumber  14  will continue to be transferred downstream to a trimmer where the lumber can be cut to size. After the lumber has exited the track  16 , the paddle  18  is returned to a starting position. 
         [0084]    In another embodiment of the method, the retrofit position fence table  48  is utilized, with a position fence  10  mounted on the table top  50 . During use, a piece of lumber  14  being transported on the conveyor is urged toward the paddle  18  traveling on track  16 . The paddle  18  prevents further movement of the lumber in a direction perpendicular to the travel of the track  16  when the locking mechanism  22  is switched to a closed position which locks the paddle  18  in place on the bearing way  20 . The paddle position sensor  30  determines the location of the locked paddle  18  and sends the information to the controller  34 . The location of the locked paddle  18  is compared to the desired location and if the location of the locked paddle  18  is not at the desired position, the track moving device  32  is activated to move the table top  50  and track  16  in a lateral direction so that the locked paddle  18  is located in the desired position without unlocking the paddle  18 . The position of the table top  50  or track  16  is confirmed using the feedback device  33 . Once the locked paddle  18  is in the desired position, the lumber  14  urged against the surface  19  of the locked paddle  18  will be in the desired position. The lumber  14  will continue to be transferred downstream to a trimmer where the lumber can be cut to size. After the lumber has exited the track  16 , the paddle  18  is returned to a starting position. 
         [0085]    While the claimed invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one of ordinary skill in the art that various changes and modifications can be made to the claimed invention without departing from the spirit and scope thereof.