Abstract:
Discloses a positioning fence for use in lumber saw mills that facilitates automated positioning of lumber for cutting. A continuous moving track loop has a plurality of paddles laterally positionable across the width of the track. Each paddle has a brake to hold the paddle in position. A positioning cam releases the brake to align each successive paddle to a desired lateral offset and a zeroing cam resets each paddle to a zero position.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates to woodworking machines and more particularly to a guide fence or stop for timber in sawmills or sawing machines.  
       BACKGROUND TO THE INVENTION  
       [0002]     In sawmills various timber handling machinery is provided to cut and shape the timber into wood products such as veneers, board products and the like. In forming a board product, the tree or flitch material is cut to the desired cross section of the three dimensional shape desired for the lumber product being produced and the piece are then cut to length. When board lumber is handled within a mill, automation is generally provided throughout the mill to transport the material to be cut or worked within the sawmill. Frequently, the board lumber is transported from one work position to another on a flat bed roller system.  
         [0003]     Once the flitch has been cut to the desired cross section, it is supplied to saw equipment for cutting to length. To cut the material to length, one arrangement of transport equipment has a conveyor that has a flat bed lug chain transport table to carry the lumber pieces toward the 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. 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. In the configuration of sawmill conveyor equipment just described, the saw is 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 barrier 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.  
       SUMMARY OF THE INVENTION  
       [0008]     The present invention provides a board positioning fence that includes individual paddles displaced along a continuous track loop at a spacing corresponding to the spacing of the lumber to be positioned or ended. The paddles are laterally displacable across the width of the track and include a brake to lock the paddle from lateral movement. When lateral adjustment is desired, a positioning cam engages the paddle to release the paddle brake allowing the released paddle travels across the track long a bearing. When the desired lateral offset amount is achieved, the positioning cam is disengaged from the paddle allowing the brake to halt further lateral displacement of the lumber in the feed assembly. A reset cam returns the paddles to a zero position on the return travel of the track loop.  
         [0009]     A preferred embodiment of the invention will now be described with reference to the accompanying drawings in which like features of the invention are depicted by the same reference numerals throughout the various figures of the drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is perspective view of a preferred embodiment of the positioning fence.  
         [0011]      FIG. 2  is an elevation view of a paddle assembly of  FIG. 1 .  
         [0012]      FIG. 3  is an end view of the positioning fence of  FIG. 1 .  
         [0013]      FIG. 4  is a plan view of the positioning fence of  FIG. 1 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0014]      FIG. 1  shows a perspective view of a preferred embodiment of the positioning fence of the present invention, generally depicted by reference numeral  10 . The positioning fences has a continuous track loop  16  extending between an opposed set of end rollers  14  supported by a frame assembly  12 . The track includes a plurality of paddles  18  spaced along the continuous track loop  16  corresponding to the lumber spacing of the individual board pieces that the board lumber position fence will be used to position. Each 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, which is the direction of movement that the lumber will move when positioned or ended using the board lumber position fence. One of end rollers  14  is driven to cause paddles  18  to move transversely, that is in the direction of travel of the lumber, which is generally depicted by arrow A. Suitable means to provide drive to an end roller includes a sprocket assembly  22  for chain coupling to a torque source, such as a drive motor or the lumber transport system that the position fence operates with or other equipment in the saw mill. To construct the continues loop track  16 , each end of bearing way  20  is coupled to a flexible web  24  extending between each of the end rollers  14 . Flexible web  24  is constructed from a belt or a chain. In this manner, the paddles  18  of the continues track are driven in the direction of arrow A.  
         [0015]      FIG. 2  shows a side elevation view of a preferred embodiment of a paddle assembly constructed in accordance with the principles of the invention, generally depicted by reference numeral  18 . The paddle assembly  18  has a bearing  26  that is slidably mounted on bearing way  20 . The sliding engagement between bearing  26  and bearing way  20  permits lateral movement of the paddle assembly  18  along bearing way  20  in the directions shown by double headed arrow B. A paddle lumber seat  28  provides a surface on which the lumber piece to be positioned rests. A pivot arm  30  interconnects the paddle lumber seat  28  with bearing  26  at pivot  32 . A brake  34  prevents movement of the paddle assembly  18  along bearing way  20  when a lumber piece rests on the paddle lumber seat  28 . A force “F” applied to the paddle lumber seat  28  and/or a biasing means  33 , such as a spring, rotates pivot arm  30  around pivot  32  urging brake  34  into contact with bearing way  20  thus preventing sliding lateral movement of the paddle assembly  18  along bearing way  20 . Brake  34  is constructed from a suitable friction material such as for example polyurethane.  
         [0016]     Each paddle assembly includes cam followers to effect movement and positioning of the paddle assembly  18  along bearing way  20 . A positioning cam follower  36  is used to urge the paddle assembly  18  in a right-to-left direction along bearing way  20  and a reset cam follower  38  is used to urge paddle assembly  18  in the opposite direction, that is, in a left-to-right direction. Engagement of cam followers  36  or  38  releases the brake  34 . For example, when a cam contacts the positioning cam follower  36  in the direction of arrow “P”, pivot arm  30  rotates to release brake  34  allowing the cam to move the paddle assembly to the left. Similarly, when a cam contacts the reset cam follower  38  in the direction of arrow “R”, pivot arm  30  rotates to release brake  34  allowing the cam to move the paddle assembly to the right. Consequently cam followers  36  and  38  are used to position the paddle assembly  18  at a desired location on bearing way  20 .  
         [0017]      FIG. 3  is an end view of a preferred embodiment of the board lumber position fence assembly  10 . A reset or zeroing cam  40  is coupled to the frame assembly  12  of the board lumber position fence. Reset cam  40  is provided for contact with the reset cam follower  38  of each paddle assembly and is used to urge each successive paddle assembly  18  that passes along it back into a zero or reset position. The zero or reset position is the position of the paddle assembly in the right most location along each respective bearing way  20 . When the paddle assembly is in the zero or reset position it can traverse in a right-to-left fashion to the other end of the bearing way as required to end or provide a lateral position to a board lumber piece.  
         [0018]     A positioning cam  41  is provided on the opposite paddle travel side of the track, that is in the upper area of the board lumber position fence. The positioning cam is moveable between a released position or a locked position. When the positioning cam segment is in the released position, it is oriented to engage the lower cam follower  36  of each successive paddle assembly  18  passing along it. When the positioning cam  41  is in the released position, it comes into contact with the positioning cam follower  36  of a paddle assembly  18  and the paddle assembly is freed to move in a right-to-left direction along bearing way  20 . In operation of the lumber positioning fence, a lumber piece  46  is seated on the paddle lumber seat  28  and is urged in the direction of arrow “F”. Thus when the positioning cam  41  is oriented into released position as shown in  FIG. 3 , it comes in contact with the position cam follower  36  and the paddle assembly  18  is freed to move in a right-to-left direction. Consequently, lumber piece  46  will then move in the direction of arrow “F” until the positioning cam  41  is oriented into a locked position, which causes the paddle assembly  18  to lock in that lateral position or location. Thus, when the desired offset or lateral displacement of the lumber piece  46  seated on paddle assembly  18  is achieved, the positioning cam  41  is actuated to release it from contact with lower cam follower  36 , thereby causing the paddle assembly  18  to lock in that location.  
         [0019]      FIG. 4  shows a top plan view of the board lumber position fence giving another view of the cam assemblies in accordance with the present invention. A top plan view of the zeroing cam  40  shows it is positioned at an angle to the direction of travel of the paddles  18  mounted on the continuous track loop  16 . As the paddles  18  travel past the zeroing cam  40 , they are urged to return to the zero position, which all paddles in the drawing are shown in with the exception of displaced or offset paddle  48 . Also visible in this drawing is the positioning cam  41 , which is set at an angle to the direction of travel of the paddles  18 . The positioning cam is orientable between a released position, which effects lateral movement of each paddle passing therealong, and a locked position, where no lateral movement of a passing paddle occurs.  
         [0020]     Preferably, the positioning cam  41  is constructed from a plurality of positioning cam segments, where each segment being orientable between a released position  42  and a locked position  52 . An actuator  50  orients a corresponding respective positioning cam segment between the released orientation  42  and the locked orientation  52 . The positioning cam segments  42  are all oriented in a released orientation or position  42 , with the exception of positioning cam segment  52 , which is in the locked orientation or position. The positioning cam is preferably provided in segments each with its own respective actuator to facilitate separate control of each individual paddle even with a shallow cam angle and close spacing of the paddles  18  along track  16 . Therefore, cam segments on the positioning cam permit gradual lateral adjustment of the lumber pieces, even with a close spacing of the paddle/lumber piece along the length of the continues track loop  16 .  
         [0021]     The locked orientation of cam segment  52  illustrates operation of the positioning fence. As the displaced or offset paddle  48  passed along the positioning cam  41 , contact of that paddle&#39;s lower cam follower with the segments of the positioning cam allowed the board lumber piece  46  (shown in dotted outline form) to move laterally and be positioned at an off set from the zero position. When the board lumber piece reaches the desired offset amount, the positioning cam segment was actuated away from contact with the cam follower of the associated paddle, causing the paddle brake to lock, thereby halting further lateral displacement of the lumber piece  46 .  
         [0022]     Now that the invention has been described numerous variations, substitutions and equivalents will come to the mind of those skilled in the art. The invention, is not however, limited to the specific embodiments described herein with reference to the attached drawings, but rather, the scope of the invention is defined by the claims appended hereto.