Abstract:
A novel sawmill carriage knee and dog positioning system using a chain knee drive that allows vertical access to chain tension adjustment screws, provides a chain mounting attachment plate connected to an adequately sized air cylinder attached to a dogs in/out carrier slide increasing structural rigidity and reducing component count, weight and unit cost, and providing a novel method to taper the knees relative to the sawline.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority of U.S. Provisional Patent Application 61/825,012, filed on May 18, 2013, the teachings and disclosure thereof herein entirely incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     A novel sawmill carriage knee and dog positioning system using a chain knee drive that allows vertical access to chain tension adjustment screws, provides a chain mounting attachment plate connected to an adequately sized air cylinder attached to a dogs in/out carrier slide increasing structural rigidity and reducing component count, weight and unit cost, and providing a novel method to taper the knees relative to the sawline. 
     BACKGROUND OF THE INVENTION 
     A sawmill carriage is generally made up of movable knees providing a vertical surface against which a log rests may rest against and movable dogs used to clamp and hold the log while the carriage reciprocates back and forth along a track parallel to a saw blade. Before each pass, the log may be moved, or “jogged” toward or away from the saw blades or set. The jogging is generally accomplished by horizontal movement of the knees toward or away from the saw blades, to the desired thickness of the cut board desired to be produced from the log. The board is cut as the log advances through the saw. This process continues until the operator or “sawyer” decides to unload what is left of the log, the left-over piece generally referred to as a “cant” or “dogboard.” 
     One dog, a “tong dog” system, comprises of an upper dog, a lower dog, a mechanism to bring the dogs together and a mechanism to move the dogs horizontally away from or towards the vertical surface of the knee. The knees themselves advance toward or away from the saw line, and is most commonly driven by a chain or rack gear. 
     The chain drive mechanism has several advantages over the rack gear system, making it the desirable mechanism by which to move the knees. The tong dog systems that use a rack gear to position the knees relative to the sawline are generally difficult to replace, not easy to adjust, and must have slack built-in even when the system is new. Comparatively, a chain drive system is easily adjustable, durable and easy to replace as wear necessitates. 
     A chain drive system must have a mechanism by which to tension the chain. As the chain drive system components and chain rollers wear, the chain will loosen and must be adjusted to prevent excessive slack. The chain tensioning mechanism adds to the complexity of the sawmill carriage, increasing the number of components necessary and necessitates a carriage structure sufficient for the force transfer from the log though the dogs and dog adjustment mechanism, through the knee components to the chain drive. A need exists for a chain drive system having a fewer components, is simple to service and adjust and provides for an efficient force transfer from the log to the chain drive to reduce number of stressed components in the sawmill carriage. 
     ADVANTAGES AND SUMMARY OF THE INVENTION 
     One distinct advantage of the inventive device is the capability thereof to function independently of any other device on demand during a sawmill tapering operation. Another advantage is the ability for such a unique device to provide sufficient strength and grip to a tapering arm while manipulating a separate tapering arm in order for a selective taper position to be established on demand (and on sight, for that matter) by an operator. Thus, another advantage of this invention is the provision of a total system that permits selective tapering positioning for more effective and efficient sawmill operations, such that, at least, greater utilization of desired wood materials of necessary configuration is permitted. 
     Accordingly, the present invention encompasses a novel sawmill carriage chain drive tensioning mechanism that allows vertical access to the chain tension adjustment screws and providing a mounting attachment point upon the same member used for chain tensioning thus reducing the amount of components having to bear the dog load during adjustment, increasing rigidity and reducing component weight and unit cost. 
     The chain drive system is preferably for use with a tong dog carriage comprising a special chain adjustment plate attached to a knee base plate and attached to an in/out dog cylinder, drive chain with an adjustment bolt attached to each end, drive sprocket and an idler sprocket. The chain adjustment plate serves as an anchor for the in/out dog cylinder and the end connector for the chain while allowing adjustments to be made to both tension and, in the preferred embodiment, to move the knee incrementally toward or away from the saw blade. The large, 4-5 inch pneumatic in/out dog cylinder allows tapering of the log cut to occur with accuracy and ease of adjustment while minimizing the overall unit cost. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is illustrated by the accompanying drawings, in which: 
         FIG. 1  is a perspective view of an embodiment of the sawmill including the sawmill carriage and log; 
         FIG. 2  is a front view of the sawmill including the sawmill carriage and log shown in  FIG. 1 ; 
         FIG. 3  is a side view of the sawmill including the sawmill carriage and log shown in  FIG. 1 ; 
         FIG. 4  is a top front perspective view of the knee, chain drive and tong dog assembly with the tong dog in the extended position; 
         FIG. 5  is a bottom front perspective view of the knee, chain drive and tong dog assembly shown in  FIG. 4 ; 
         FIG. 6  is a side view of the knee, chain drive and tong dog assembly with the tong dog in the extended position; 
         FIG. 7  is a top perspective view of the knee, chain drive and tong dog assembly shown in  FIG. 6  with the lower dog left support member removed; 
         FIG. 8  is a side view of the knee, chain drive and tong dog assembly with the tong dog in the retracted position; 
         FIG. 9  is a top perspective view of the knee, chain drive and tong dog assembly shown in  FIG. 8  with the lower dog left support member removed; 
         FIG. 10  is a bottom perspective view of the knee, chain drive and tong dog assembly shown in  FIG. 8 ; 
         FIG. 11  is a top perspective view of the knee, chain drive and tong dog assembly with the lower dog left support member, tong dog slide plate and guides removed; 
         FIG. 12  is a top front exploded perspective view of the lower tong dog slide plate, lower knee support plate, chain drive and tensioning plate; 
         FIG. 13  is a top front perspective view of the lower tong dog slide plate, lower knee support plate, lower knee slide plates, chain drive and tensioning plate; 
         FIG. 14  is a top front exploded perspective view of the lower tong dog slide plate, lower knee support plate, lower knee slide plates, chain drive and tensioning plate; 
         FIG. 15  shows a partial view of the tensioning plate and lower tong dog slide plate; 
         FIG. 16  shows a side perspective view of the tensioning plate and chain; 
         FIG. 17  shows a partial view of the tensioning plate and chain; and 
         FIG. 18  shows is an electric schematic for the dog control circuit used when tapering. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The drawings illustrate a sawmill carriage unit for cutting a log into lumber. The carriage moves linearly upon a rail or track allowing a saw blade, or plurality of saw blades to cut the log into boards of a desired thickness. It should be understood that the saw blade may be a circular saw blade, a band saw blade or any other blade suitable for cutting a log. 
       FIG. 1  shows a sawmill carriage  1  and log  3  to be cut. The sawmill carriage  1 , having movable knees  101  with built-in movable dogs ( 203 ,  205  of  FIG. 2 ) is used to clamp and hold the log  3 . The carriage wheels  11  rest upon a track (not shown) parallel to a saw blade. The carriage  1  reciprocates back and forth along the track parallel to a saw blade. Before each pass through the saw, the knees  101  can be “jogged” toward or away from the saw or “set” which advances the knees  101  toward the saw an amount equal to the desired thickness of a board. The board is cut from the log as the log  3  advances through the saw. This process continues until the sawyer decides to unload the remainder of the log  3 , the remainder of the log generally referred to as a “cant” or “dogboard”. 
     In general, most all logs are tapered from one end to the other, as the log  3  shown in  FIG. 1  is tapered from a wide end  5  to a narrow end  7 . For each log, the sawyer must choose how to taper or pivot (i.e. position) the log relative to the saw. The sawyer will move the small end  7  of the log  3  closer to the saw or the large end  5  of the log  3  away from the saw when adjusting the taper before cutting. 
       FIG. 2  shows a front view of the invention  1 . The preferred embodiment of the invention uses a plurality of pairs of opposing dogs  203 ,  205  extending from the front face ( 103  of  FIG. 3 ) of each knee  101 . Each pair of opposing dogs comprises an upper dog  203  and an opposing lower dog  205 . The dogs  203 ,  205  move towards each other to clamp onto the log  3 , by means of an actuator or cylinder, preferably a pneumatic air up/down cylinder  31 . 
       FIG. 3  shows a side view of the invention showing the right most knee  101  and narrow end  7  of the log  3 . The dogs  203 ,  205  are shown in a clamped down position, extending from the front face  103  of each knee  101 . 
       FIG. 4  shows a front top side perspective view of a knee  101  showing an in/out cylinder  41  attached to a chain tension adjustment plate  51 . The chain adjustment plate  51  allows adjustment of the tension of the chain  21  by tightening or loosening an adjustment bolt. In the preferred embodiment, shown here, there are two adjustment bolts, the first bolt  63  attached to a first end of the chain  21  and a second bolt  65  attached to a second end of the chain  21  allow adjustment of the chain  21  both for tension and also horizontal position of the knee relative to the other knees. To adjust tension or remove slack, tighten both adjustment bolts  63 ,  65  equally. When a plurality of knees are driven by a common actuator, it is desirable to be able to adjust the knees in small increments so as to be able to align the front face of each knee in plane with one another. Having one chain adjustment screw on either end of the chain enables a user to make small adjustments to ensure each knee is properly aligned. This is accomplished by tightening one bolt while simultaneously loosening the other  63 ,  65 . The vertical position of the bolts  63 ,  65  provide easy access. The adjustment plate is secured to the knee base plate  111  and attached to the in/out cylinder  41  preferably by a pinned connection  233 . 
     The in/out cylinder  41  is preferably a pneumatic cylinder having a minimum diameter of 4 to 5 inches. The in/out cylinder  41  in the preferred embodiment is larger than is typically used for positioning of dogs in a traditional sawmill, but the added diameter greatly aids in maintaining the dog  203 ,  205  position when adjusting the knees to taper the log to the desired angle. The chain adjustment plate  51  position and narrow profile provides space to use an adequately sized in/out cylinder  41 , capable of holding log in a tapered position, which is critical to the novel method of tapering presented later. 
     In the preferred embodiment, the in/out cylinder  41  is a pneumatic cylinder allowing rapid adjustment of the dogs  203 ,  205 , and when compared to other actuators such as a hydraulic actuators, the pneumatic system is less expensive, faster acting and reduces the likelihood of oil contamination of the wood. The lower dog  205  is slide-ably retained to the knee base plate  111  while the upper dog  203  is retained by a pin connection  215  to the lower dog  205 . In this figure, the dogs  203 ,  205  are in an extended position. 
       FIG. 5  shows a front bottom side perspective view of the knee shown in  FIG. 4  showing the chain  21  bottom of the knee base plate  111 , base plate guides  113 ,  115  and the lower portion of the chain tension adjustment plate  51 . The chain tension adjustment plate  51  extends downwardly past the knee base plate  111  allowing the chain to travel in a linear direction between a first sprocket  81  and a second sprocket or idler pulley  83 . The second sprocket may possess teeth, or may be without teeth. A hydraulic motor  85  may be used to move the knee toward or away from the saw cut plane. 
       FIG. 6  shows a side view of the knee shown in  FIGS. 4 and 5 . In the preferred embodiment, the upper dog  203  is connected to an intermediate connecting member  211  by an upper pin connection  213  and the lower dog  205  is connected to the intermediate connecting member  211  by a lower pin connection  215 . In the preferred embodiment, the in/out cylinder  41  is connected to the intermediate connecting member  211  by a pin connection  231  on a first end of the cylinder  41  and to the chain adjustment plate  51  by a pin connection  233  on a second end of the cylinder  41 . The up/down cylinder  31  is rigidly connected to the upper dog  203  and pin connected to the lower dog  205 . The in/out cylinder  41  extends, pushing against the chain adjustment plate  51  and intermediate connecting member  211  which moves the dogs  203 ,  205  toward the knee front face  103 . When the in/out cylinder  51  contracts, it pulls against the chain adjustment plate  51  and intermediate connecting member  211  moving the dogs  203 ,  205  away from the knee front face  103 . 
       FIG. 7  shows a top perspective view of the knee assembly  101  showing the dogs  203 ,  205  in an unclamped, extended state. The right lower dog horizontal member  251  is shown but the left lower dog horizontal member is not shown for clarity. The intermediate connecting member  211 , linearly slides along the knee base plate  111  allowing the dogs  203   205  to move toward and away from the knee front face  103 . In the preferred embodiment, the intermediate connecting member guides  221 ,  223  retain the intermediate connecting member base plate  212  ( FIGS. 11, 12, and 13 ) which is rigidly attached to the intermediate connecting member  211  and allow the horizontal linear movement of the intermediate connecting member  211  when pushed or pulled by the in/out cylinder  41 . The chain  21  anchors the chain adjustment plate  51  in place. The chain  21 , and also with it, the knee  101  and dogs  203 ,  205 , can be moved as a unit by the operator to a desired position by a hydraulic motor  85 . 
       FIG. 8  shows a left side view of the knee  101  with the dogs  203 ,  205  in an open, retracted position, pulled close to the knee face  103 . An idler pulley  87  attached to a second sprocket  83  placed opposite of the chain actuator  85  and first sprocket  81  allow horizontal movement of the knee  101 . The left lower dog horizontal member  255  is shown. 
       FIG. 9  shows a top perspective view of the knee assembly  101  showing the dogs  203 ,  205  in an retracted position. The right lower dog horizontal member  251  is shown but the left lower dog horizontal member is not shown for clarity. The intermediate connecting member  211 , linearly slides along the knee base plate  111  allowing the dogs  203   205  to move toward and away from the knee front face  103 . In the preferred embodiment, the intermediate connecting member guides  221 ,  223  retain the intermediate connecting member base plate  212  which is rigidly attached to the intermediate connecting member  211  and allow the horizontal linear movement of the intermediate connecting member  211  when pushed or pulled by the in/out cylinder  41 . The chain  21  anchors the chain adjustment plate  51  in place. The chain  21 , and also with it, the knee  101  and dogs  203 ,  205 , can be moved as a unit by the operator to a desired position by a hydraulic motor  85 . 
       FIG. 10  shows a bottom perspective view of the knee assembly  101  with the intermediate connecting member base plate, left lower dog horizontal member and right lower dog horizontal member removed for clarity. The chain adjustment plate is shown having a front lower protrusion  53  and a rear lower protrusion  55  extending down below the knee wear plate. The protrusions  53 ,  55  allow the chain to maintain a linear relationship with the top of the sprockets  81 ,  83  allowing the chain to horizontally move the knee toward or way from the saw blade or saw set. 
       FIG. 11  shows a top perspective view of the knee base plate  111 , intermediate connecting member  211 , intermediate connecting member base plate  212 , chain tension adjustment plate  51 , chain  21 , and hydraulic motor  85 . The intermediate connecting member base plate  212  straddles the chain tension adjustment plate  51  giving the intermediate connecting member  211  additional stability. A slot  113  in the knee wear base plate  111  allows the lower dog to retract flush with the knee face while also open to a position at or below the knee wear base plate  111 . 
       FIG. 12  shows a top perspective assembly exploded view of the knee base plate  111 , intermediate connecting member  211 , intermediate connecting member base plate  212 , chain tension adjustment plate  51 , chain  21 , and hydraulic motor  85 . The intermediate connecting member base plate  212  possesses a slot  271 . The slot  271  results in the left side  273  and right side  275  of the intermediate connecting member base plate  212  to extend past the chain tension adjustment plate  51 . 
       FIG. 13  shows a top perspective view of the knee base plate  111 , intermediate connecting member  211 , intermediate connecting member base plate  212 , chain tension adjustment plate  51 , intermediate connecting member base plate left and right guides  221 ,  223 , left and right knee wear plates  133 ,  135  and left and right knee wear plate guides  137 ,  139 . The intermediate connecting member left guide  221  and right guide  223  restrict the movement of the intermediate connecting member  211  to a linear motion towards and away from the knee front face  103 . The knee wear base plate  111  is restricted to a linear movement toward and away from the saw blade by a left knee wear plate guide  137  and a right knee wear plate guide  139  which capture a left wear plate  133  and a right wear plate  135 . 
       FIG. 14  shows an exploded assembly perspective view of the knee base plate and  111  and left and right intermediate connecting member guides  221 ,  223 . The intermediate connecting member guides  221 ,  223  are secured to the knee base plate by bolts  141  through the top restraining members  143 ,  163 , allowing for disassemble for maintenance or repair of wear surfaces  145 ,  165  or addition and/or removal of shim members  147 ,  167  to lateral restraining members  149 ,  169 . The guides  221 ,  223  capture the intermediate connecting member base plate  141  preventing unwanted lateral or vertical movement or rotation while allowing horizontal movement toward or away from the knee front face relative to the knee wear base plate  111  as permitted by the in/out cylinder. 
       FIG. 15  shows a perspective partial close up view of the knee; chain tension adjustment plate  51 , knee wear base plate  111  and intermediate connecting member  211 , intermediate connecting member base plate  212  and intermediate connecting member guides  221 , 223 . The chain tensioning plate  51  possesses a first chain tensioning screw  63  and a second chain tensioning screw  65 . The two screws  63 ,  65  allow for adjustment of the chain  21  tension and also for horizontal adjustment of the knees. The screws  63 ,  65  are vertically positioned down through the chain adjustment plate top surface  71  allowing the user to easily access the tension screws from above and easily make alternating incremental adjustments to the screws, such as loosening one while tightening the other to adjust the knee&#39;s horizontal position while maintaining proper tension. The proximity of the screws  63 ,  65  to each other and their vertical orientation speeds up and simplifies chain  21  adjustment. 
     The chain tension adjustment plate  51  possesses an aperture  235  for receiving a pin connection to the in/out cylinder. The chain adjustment plate has a left surface  73  and a right surface  75 , a rear surface  77  and a front surface  79 , the distance between the right and left surfaces  73 ,  75  being shorter than the distance between the rear and front surfaces  77 ,  79  creating a chain tensioning plate having a narrow profile. The narrow profile of the plate  51  enables the intermediate connecting member base plate  212  to straddle the plate  51 , the intermediate connecting member base plate left side  273  and right side  275  extending to either side opposing the left and right surfaces  73 ,  75  of the plate  51  respectively. This arrangement creates a stronger intermediate base plate  212  with a larger wear surface area and less undesired play, or looseness. The narrow chain tensioning plate allows additional room for a larger in/out cylinder, necessary for adequate force to move the dogs in/out and hold a log in tapered position not possible with prior art designs. 
       FIGS. 16 and 17  show the chain tension adjustment plate  51  (which is preferably, though not necessarily a ⅜ th  inch steel block), chain  21  (which is preferably, though not necessarily a #100 chain), idle sprocket or pulley  87 , and rotary actuator  85 . The tension screws  63 ,  65  protrude through the top 71 of the chain tension adjustment plate  51  providing chain position adjustment and tension adjustment. The front inner surface  80  of the chain tension adjustment plate  51  possesses a radius  93  allowing the chain to bend along the surface of the radius  93  to allow adjustment. Likewise, the rear inner surface  78  possesses a radius  91  allowing the chain to bend along the surface of the radius  91  to allow the chain to slide along the surface of the radius  91  for adjustment. The chain tension adjustment plate  51  further possesses an aperture  235  for receiving a pin connection to the in/out cylinder. 
     The invention enables a sawyer to quickly and efficiently cut logs at a desired taper without the aid of a more complex, expensive machine by allowing the sawyer to utilize the knee positioning actuator to precisely and quickly adjust the taper of the saw cut. 
     In the preferred embodiment of the invention, each dog, or set of dogs, on a single knee is able to be controlled independent of the dog, or set of dogs, on the other knees. The user is able to control the movement of the dogs on/off switches, along with a jog button to taper the log therefore eliminating the complex mechanical assemblies used to typically taper the log. With the present invention the sawyer tapers the log by: 
       FIG. 18  is the electric schematic for the dog control circuit used when tapering. Sawyer presses dogs up/down toggle button to cause dogs to open on each knee. On the knee closest to the large end of the log, turn dog control switch off which disables the up/down control of the particular dog selected and causes the dog to close and clamp the large end of the log. 
     To taper the position of the log, the sawyer jogs away from the saw. The small end of the log, being unclamped (not dogged) pulls away from the knee face as the large (clamped) end is pulled back. 
     When the sawyer is satisfied with the taper position of the log, the sawyer turns the dogs up\down switch off which causes the dog(s) closest to the small end of the log to come down and clamp the log in place. The small end of the log will be clamped in a position away from the face of the knee which will provide the desired taper. 
     The sawyer saws the desired number of boards and then flips the dog enable switch that was previously turned off back on. Now the sawyer presses the dogs up/down switch which causes all the dogs to come up. The sawyer turns the log and repeats the process on the second axis of the log if desired. 
     The inventive system is unique because it does not use any mechanical mechanism to taper the log by tapering the knees relative to each other. Such a system utilizes the same air cylinder to move the dogs in/out and for the variable tapering of the log and the knees always stay in line during utilization. The overall system furthermore also uses simple on/off switches to control the up/down dogs and the forward/reverse jog function to position the knees. Thus, the inventive carriage dog design, when utilizing an adequately sized air cylinder to move the dogs from the “in” position to the “out” position, is critical to this tapering method, ostensibly because it provides ample stiffness to the held tapered log so as not to give or release to any appreciable degree when using the knees to position the log and hold it in place while sawing the subject log. In this manner, then, the overall system improves significantly on the current state of the art devices through the ability to selectively maneuver the subject log to any taper position on demand through the chain drive component present herein.