Abstract:
A bi-directional cutting band mill apparatus utilizes two band saws mounted on a carriage for cutting horizontal sections from logs through successive back and forth passes across each log as the carriage reciprocates on a lower frame wherein a section of the log is cut with one band saw in one pass and then a next section of the lumber is cut by the other band saw as the carriage travels in the opposite direction in the following pass. The bi-directional cutting band mill apparatus includes structural elements that allow for the coincident raising and lowering of both band saws and structural elements that provide for the sequential and incremental adjustment of each band saw preparatory for cutting the sections from the log so that each respective band saw can be positioned for making the appropriate depth of cut through the section of the log during that respective pass of the respective band saw.

Description:
FIELD OF THE INVENTION 
     The present invention pertains to timber and log cutting devices, and, more particularly, pertains to a device having two adjustable cutting blades mounted on a traveling carriage for cutting horizontal sections from logs in successive back and forth passes. 
     BACKGROUND OF THE INVENTION 
     The transformation of logs and raw timber into lumber, and thence into wood products that range from baseball bats and boxes, furniture and flooring, pencils, baskets, crates and pallets, comprises a number of steps from forest to sawmill and from sawmill to lumberyard, and thence to the manufacturing, chemical or paper plant or factory. 
     Even with modern equipment and machinery one of the most difficult steps in the logging process involves the transportation of the felled trees (logs) from the forest or woods to the sawmill. The lumbermen generally must skid the logs from the site where they have been cut to a landing (a central location in the woods or forest) for transportation to a sawmill usually by securing the logs to a log skidder that conveys the logs to the landing. The logs can also be placed on sleds, with the sleds then being attached to the log skidders for transport to the landing and thence to the sawmill. This necessitates the cutting of trails or roads through the woods or forest for connecting the logging site to the landing. Additional trails or roads may need to be cut for connecting the landing to a highway if the logs are of sufficient length and diameter that they require transport to the sawmill by a heavy duty log carrying tractor trailer. 
     In view of the above, it is advantageous to cut the logs into manageable pieces of lumber either on site or at the landing in order to facilitate the removal of the logs from the forest. However, this requires that some type of cutting or sawing unit, such as a band saw, be available for transport to the logging site or landing for performing the requisite log cutting. Thus, the cutting or sawing unit should be portable as logging sites are often located in rugged terrain and remote areas. Such a cutting or sawing unit should also be adaptable for use at smaller sites such as wood lots that are usually located on a portion of a tract of farmland. The size of the cutting or sawing unit should preferably be such as to minimally disturb or disrupt the tract of farmland as the unit is being taken to the site for log cutting and removal therefrom when the log cutting is completed. 
     SUMMARY OF THE INVENTION 
     The present invention comprehends a bi-directional cutting band mill utilizing two saw blades for cutting sections from a log by consecutive reciprocable passes of the saw blades. 
     The band mill of the present invention includes a lower frame or spaced-apart guide rails for placement on the ground or that are part of a wheelable trailer assembly. Supported on the lower frame for reciprocable movement thereon is a carriage or framework. In the preferred embodiment the carriage moves over the log during the successive cutting operations on the log. The carriage includes stanchion members that ride upon the lower frame and that are interconnected by cross members that support thereon the main saw blade motor and other structural elements that cooperate to raise, lower, and adjust both saw blades. 
     Mounted to the stanchion members and spanning the lower frame is a pair of spaced-apart band saws with the teeth of each band saw generally facing inward toward each other. The band saws are driven by the main saw drive motor and an interconnected pulley and belt system including a drive pulley and main drive belt and ancillary band saw belts and pulleys. 
     The band saws are capable of being simultaneously raised and lowered as a unit so that they can be lifted completely above the log, and the band saws are also capable of selective incremental adjustment for cutting through the log at the desired depth. In order to simultaneously lift both band saws the band saws are interconnected to each other by a pair of lift bars. Each lift bar is pivotally mounted to a guide, and each guide is slidably mounted to the stanchion members so that when both guides slide upward on the respective stanchion members by a lift motor and chain arrangement, the coincident raising of both band saws occurs and when the guides slide downward on the respective stanchion members the coincident lowering of both band saws results. 
     In addition, the band saws are capable of individual selective incremental adjustment to obtain the desired depth of cut through the log. A manually operable rack and pinion arrangement permits the operator to position in turn each band saw adjacent the end of the log for the desired depth of cut while simultaneously lifting the other band saw above the log so the cut can be made. As successive sections of the log are cut one band saw is utilized for the cutting while the other band saw is positioned above the log and passes over the log. After the cut is completed the positions of the band saws are changed for the next pass, in the reverse direction, by the band saws for making the next cut. 
     It is an object of the present invention to provide a band mill that employs two band saws for cutting logs in both directions of travel in order to reduce unnecessary cutting motion and increase productivity in cutting successive sections of the log. 
     It is another object of the present invention to provide a band mill capable of cutting logs in back and forth passes that utilizes the less expensive type of band saw that has teeth on only one side as opposed to the more expensive saw blades that have teeth on both sides. 
     It is still another object of the present invention to provide a band mill for bi-directional cutting wherein one saw blade is turned inside out prior to mounting on the carriage so that the teeth on both band saws are on opposite sides thus allowing the band mill to cut logs in both directions of travel. 
     Yet another object of the present invention is to provide a band mill wherein the sawdust produced during the back and forth cutting movements is discharged in the same direction by both blades. 
     Yet still another object of the present invention is to provide a band mill that uses the same power source and drive elements for making log cuts in both directions of travel of the carriage and the band saws. 
    
    
     These and other objects, features, and advantages will become apparent upon a perusal of the following detailed description read in conjunction with the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the bi-directional cutting band mill unit of the present invention showing the band mill unit mounted on a portable trailer frame. 
     FIG. 2 is a perspective view of the bi-directional cutting band mill unit mounted on the trailer frame and in the process of making a pass across a log for cutting a first section from the log. 
     FIG. 3 is a perspective view of the bi-directional cutting band mill unit illustrating one band saw frame and band saw in the raised disposition and one band saw frame and band saw in the lowered disposition. 
     FIG. 4 is a top plan view of the bi-directional cutting band mill unit first shown in FIG.  1 . 
     FIG. 5 is a sectioned elevational of the bi-directional cutting band mill unit taken along lines V—V of FIG. 4 illustrating one band saw frame and band saw in the raised disposition and the other band saw frame and band saw in the lowered disposition. 
     FIG. 6 is a sectioned elevational view of the bi-directional cutting band mill unit taken along lines V—V of FIG. 4 illustrating the disposition of the band saw frames and band saws level with each other in the raised disposition. 
     FIG. 7 is a sectioned elevational view of the bi-directional cutting band mill unit taken along lines V—V of FIG. 4 illustrating the disposition of the band saw frames and band saws opposite of their disposition illustrated in FIG.  5 . 
     FIG. 8 is a sectioned elevational view of the bi-directional cutting band mill unit taken along lines V—V of FIG. 4 illustrating the disposition of the band saw frames and band saws level with each other and in the lowered disposition. 
     FIG. 9 is a sectioned elevational view of the bi-directional cutting band mill unit taken along lines V—V of FIG. 4 illustrating both band saw frames and band saws in the fully raised disposition and the interaction of the bearings with the lower frame members. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Illustrated in FIGS. 1 through 9 is saw mill apparatus  10  for cutting logs  12  into manageable and transportable sections or pieces of lumber for further processing at a sawmill. Apparatus  10  generally cuts logs  12  horizontally and lengthwise by reciprocating, back and forth passes across and over the stationary log  12 ; however, while it is possible for log  12  to be conveyed into apparatus  10  for cutting, the preferred manner of cutting is for log  12  to remain stationary as apparatus  10  passes across log  12  in continuous back and forth movements. 
     As shown in FIGS. 1 through 9 apparatus  10  of the present invention includes a band mill cutting unit or machine  14  for cutting sections from log  12 . Band mill cutting machine  14  can rest upon the ground surface by the use of a lower frame that includes at least two elongated, spaced-apart guide rails or lower frame members  16 , as shown in FIGS. 2,  3  and  9 . Band mill cutting machine  14  can also be utilized as a portable cutting unit mounted on trailer frame  18  that includes wheels  20  and trailer hitch  22  for allowing band mill unit  14  to be towed and transported to various timber sites by logging trucks and other vehicles. Trailer frame  18  can also include cross members  24  for supporting log  12  thereon during cutting. 
     With reference to FIGS. 1 through 9, band mill cutting unit  10  includes a movable carriage or framework  26  that rides upon the lower frame members or guide rails  16  in a linear, back and forth or reciprocable motion and can be actuated for movement thereon by any of a variety of mechanical, electromechanical, hydraulic, and pneumatic means conventional and well known in the field. Carriage  26  includes at least two spaced-apart lower carriage members  28  that travel or ride on or against guide rails  16  and essentially maintain the alignment of carriage  26  on guide rails  16 . A series of bearings  30  journaled and mounted in bearing frames or supports  32  are used to facilitate the reciprocable motion of carriage  26  on guide rails  16 . Attached to and extending upwardly from each lower carriage member  28  are a plurality of stanchion members  34  that can be tubing, bars or rods adjoined to each other in some known manner such as by welding. Stanchion members  34  form the side supports for carriage  26 . Interconnecting stanchion members  34  are a plurality of cross frame members  36 . Cross frame members  36  extend transverse to lower frame members  16  and are located so as to pass above log  12  during the reciprocable movement of carriage  26  along guide rails  16 . In addition, several upper cross frame members  38  extend across carriage  28  adjacent the uppermost ends of the opposed stanchion members  34  in order to further interconnect stanchion members  34 , provide stability for carriage  26 , and serve as platforms for structural elements hereinafter further described. 
     Illustrated in FIGS. 1 through 9 is a pair of band saws  40  for cutting logs  12  by continuous back and forth passes across log  12 . Each band saw  40  is mounted to stanchion members  34  by band saw frame  42 , and each band saw frame  42  includes tubular portions  44  that ride upon selected stanchion members  34  in order to facilitate the raising and lowering of band saws  40 . Each band saw  40  has teeth on only one side of the blade; and band saws  40  can be mounted on band saw wheels  46  so that the teeth of band saws  40  can face inward toward each other or outward away from each other. The preferred manner of mounting band saws  40  is to have the teeth of each band saw  40  face inward toward each other. As will be more fully described hereinafter, band saws  40  are capable of being raised and lowered simultaneously as a unit concomitant with the simultaneous raising and lowering of each band saw frame  42 . Each band saw  40  is also capable of selective incremental adjustment to obtain the desired depth or level cut lengthwise through log  12 . 
     As shown in FIGS. 1 through 9, the means to raise and lower each band saw frame  42  and adjoined band saw  40  simultaneously as a unit includes numerous cooperating elements. The band saw raising and lowering means includes a pair of guides  48  with each guide  48  mounted on a respective stanchion member  34  (generally the central stanchion member) for slidable upward and downward movement thereon. A band saw adjustment bar or lift bar  50  is pivotally mounted on each guide  48  with the pivot point of each bar  50  being at the center of the respective lift bars  50  where they mount to guides  48 . Each lift bar  50  is further defined by opposed distal ends  52 , and pivotally secured to each distal end  52  is A link arm  54  so that each lift bar  50  has one link arm  54  connected to each distal end  52 . The lowermost ends of link arms  54  are in turn pivotally connected to the respective band saw frames  42 . 
     As illustrated in FIGS. 1 through 9, in order to raise and lower both band saw frames  42  and band saws  40  platform  56  is supported on upper cross frame members  38 , and disposed on platform  56  are two lift motors  58  (12 volt motors with one for raising and one for lowering), gearbox  60  interconnected to lift motors  58 , and lift shaft  62  drivingly interconnected to lift motors  58  through gear box  60 . In addition, one lift pulley  64  is drivingly interconnected to lift motors  58  and gearbox  60 . Projecting axially from gearbox  60  is lift shaft  62  for selective rotational motion to raise or lower band saws  40  and band saw frames  42 . The distal end of lift shaft  62  is supported on the uppermost portions of stanchion members  34  by lift shaft mounting bracket  66 . Mounted to lift shaft  62  is a pair of lift shaft sprockets  68  that rotate coincident with lift shaft  62 . Passing about each lift sprocket  68  is a cord, link or chain  70 . Each chain  70  has a lower chain end attached to each guide  48  so that rotation of lift shaft  62  in one direction causes chains  70  to be wound about the respective lift sprocket  68  thereby pulling guides  48  upward and, as a result, raising both band saw frames  42  and band saws  40  interconnected to the respective band saw frames  42 . Rotation of lift shaft  62  in the opposite direction causes chains  70  to unwind on sprockets  68  thereby causing guides  48  to slide downward and, as a result, lowering both band saw frames  42  and band saws  40  on stanchion members  34 . During the initial positioning of band saws  40  relative to log  12  and before the cutting operation, both band saws  40  may need to be raised above log  12  and then both before and after each cutting pass by carriage  26 , band saws  40  will need to be further adjusted to bring each band saw  40 , in turn, adjacent to log  12  for the subsequent fine adjustment prior to that particular pass. 
     In addition to the means for raising and lowering both band saw frames  42  and band saws  40  as a unit, bi-directional band mill  14  of the present invention also includes a means for achieving a selective incremental adjustment of each band saw  40  prior to cutting a section from log  12 . It should be noted that the means for obtaining selective incremental adjustment of each band saw  40  operates independently of the means for raising and lowering band saw frames  42  and band saws  40 . Thus, the selective incremental adjustment means includes a pair of rack bars  72  interconnected to only one band saw frame  42  for providing selective upward and downward movement of each band saw frame  42  and band saw  40  cooperating together as unitary feature. Rack bars  72  are located inboard of one band saw  40  and adjacent to opposed stanchion members  34 . Because band saw frames  42  are interconnected to each other through link arms  54  and link or adjustment bars  50 , rack bars  72  only need to be interconnected to one band saw frame  42  as the movement (upward or downward) for incremental adjustment of one band saw frame  42  is perforce transferred (for movement in the opposite direction) to the other band saw frame  42  and band saw  40 . 
     As shown in FIGS. 1 through 9, the means for selective incremental adjustment of each band saw  40  also includes an integral crank and drive sprocket unit whereby crank  74  is manually operable to rotate a pair of adjacent and coaxially mounted drive sprockets  76 . Meshed with each rack bar  72  is a pinion  78 , and pinions  78  are drivingly interconnected to one drive sprocket  76  by an endless linked chain  80 . Chain  80  is mounted to that drive sprocket  76  and a first sprocket  82 , and first sprocket  82  is coaxially mounted on pinion shaft  83  with both pinions  78 . The other drive sprocket  76  is drivingly interconnected to a second sprocket  84  by a second linked chain  86 . Thus, it can be seen that manual rotation of crank  74  transfers rotational motion to drive sprockets  76  and endless linked chains  80  and  86  that in turn causes rotation of pinions  78  on drive shaft  83 . Manual rotation of crank  74  in one direction raises one band saw frame  42  and band saw  40  unit while lowering the opposite band saw frame  42  and band saw  40  unit; and rotation of crank  74  in the opposite direction reverses the raising and lowering movements. Because both band saw frames  42  and band saws  40  are pivotally interconnected by lift bars  50 , rack bars  72  only need to engage one band saw frame  42  as up or down movement is transferred to the other band saw frame  42  and band saw  40  through the pivotal motion of both lift bars  50 . Incremental adjustment of each band saw frame  42  and band saw  40  is necessary after each complete lengthwise pass across log  12  by carriage  26  so that for the next pass by carriage  26  in the reverse or return direction, that particular band saw  40  is located at the appropriate level or depth to cut the next section from log  12 . 
     As shown in FIGS. 1 through 4, band mill unit  14  includes a saw drive motor  88  having a main drive belt  90  mounted on a main drive pulley  92 . In addition, two pairs of band saw pulleys  94  are used with one pair of band saw pulleys  94  associated with and driving each band saw  40 . Each pair of band saw pulleys  94  is drivingly interconnected by respective band saw pulley belts  96 . Furthermore, one band saw pulley  94  from each pair is coaxially mounted with main drive pulley  92  on main drive shaft  98 . 
     Illustrated in FIGS. 2 through 4 are belt guards  100  for each pair of band saw pulleys  94  and main drive pulley  92 . Guards  100  serve as substantially enclosed protective pockets for band saw pulleys  94  and belts  96  as the belts travel on the respective pulleys  94 . Furthermore, each pair of guards  100  serves as guides for pulley belts  96  so that when each band saw frame  42  and band saw  40  is lifted or raised up to the non-driving position, belt  96  disengages from band saw pulley  96 . When that respective band saw frame  42  and band saw  40  are lowered to the driving position, guards  100  maintain the alignment of pulley belt  96  and guide pulley belt  96  back on to pulleys  94  thereby reseating within belt  96  on that respective set of band saw pulleys  94 . 
     The foregoing description discloses and describes a preferred embodiment for the invention, and those skilled in the art will understand that other variations and modifications may be possible and practicable, and still come within the ambit of the invention.